© World Health Organization 2021. Some rights reserved. This work is available under the CC BY-NC-SA 3.0 IGO licence.
WHO reference number: WHO/2019-nCoV/prophylaxes/2021.1
Contents
1. Summary: what is this living guideline?........................................................................................................................................................................... 3
2. Abbreviations ........................................................................................................................................................................................................................ 5
3. Background............................................................................................................................................................................................................................ 5
3.1 What triggered this version of the guideline? ................................................................................................................................................... 5
3.2 Who made this guideline?...................................................................................................................................................................................... 5
3.3 How to use this guideline?..................................................................................................................................................................................... 6
4. Methods: how this guideline was created ...................................................................................................................................................................... 6
4.1 Special methodological considerations for recommendations on prophylactic interventions............................................................... 8
5. The latest evidence .............................................................................................................................................................................................................. 9
6. Who do the recommendations apply to?......................................................................................................................................................................11
7. Recommendations for prophylaxis.................................................................................................................................................................................12
7.1 Hydroxychloroquine ..............................................................................................................................................................................................12
8. Uncertainties, emerging evidence and future research .............................................................................................................................................14
9. Authorship, contributions and acknowledgements....................................................................................................................................................14
References................................................................................................................................................................................................................................17
Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
1. Summary: what is this living guideline?
Clinical question: What is the role of drugs for preventing COVID-19?
Target audience: The target audience is clinicians and health care decision-makers.
Current practice: Current use of drugs to prevent COVID-19 is variable, reflecting large-scale uncertainty. Numerous randomized trials
of many different drugs are underway to inform practice. This first version of the Drugs to prevent COVID-19: A WHO living guideline
contains new information and a recommendation on hydroxychloroquine (1). It follows the publication of six trials synthesized in a living
network meta-analysis (NMA).
Recommendations: The panel made a strong recommendation against the use of hydroxychloroquine prophylaxis for individuals who do
not have COVID-19 (high certainty evidence).
How this guideline was created: This living guideline is an innovation from the World Health Organization (WHO), driven by the urgent
need for global collaboration to provide trustworthy and evolving COVID-19 guidance informing policy and practice worldwide. WHO
has partnered with the non-profit Magic Evidence Ecosystem Foundation (MAGIC) for methodologic support and development and
dissemination of living guidance for COVID-19 drugs to prevent and treat COVID-19. These guidelines are also published in the BMJ
(2), supported bytwo living systematic reviews with network analysis that inform the recommendations (3, 4). An international
Guideline Development Group (GDG) of content experts, clinicians, patients, an ethicist and methodologists produced
recommendations following standards for trustworthy guideline development using the Grading of Recommendations Assessment,
Development and Evaluation (GRADE) approach. No conflict of interest was identified for any panel member or other contributors to
the guideline development process.
The latest evidence: The recommendation on hydroxychloroquine was informed by results from a systematic review and NMA that
pooled data from six trials with 6059 participants who did not have COVID-19 and received hydroxychloroquine (3). Three trials
enrolled participants who had a known exposure to infection.
The resulting GRADE evidence summary suggested that hydroxychloroquine has a small or no effect on mortality (odds ratio 0.70; 95%
CI 0.24–1.99; absolute effect estimate 1 fewer death per 1000, 95% CI from 2 fewer – 3 more deaths per 1000 individuals; high
certainty evidence) and on admission to hospital (odds ratio 0.87; 95% CI 0.42–1.77; absolute effect estimate 1 fewer per 1000, 95% CI
3 fewer – 4 more admissions to hospital per 1000 individuals; high certainty evidence). Hydroxychloroquine probably has a small or no
effect on laboratory-confirmed SARS-CoV-2 infection (odds ratio 1.03; 95% CI 0.71–1.47; absolute effect estimate 2 more per 1000;
95% CI 18 fewer – 28 more infections per 1000 individuals; moderate certainty evidence). In contrast, hydroxychloroquine probably
increases adverse events leading to discontinuation (odds ratio 2.34; 95% CI 0.93–6.08; absolute effect estimate 19 more per 1000,
95% CI 1 fewer – 70 more adverse events per 1000 individuals; moderate certainty evidence).
There was no indication of a credible subgroup effect based on known exposure to a person with SARS-CoV-2 infection or
hydroxychloroquine dosing regimen (extremely low event rates precluded investigation of subgroup effects for mortality).
Understanding the recommendations: When moving from the evidence to the strong recommendation against the use of
hydroxychloroquine to prevent COVID-19, the panel emphasized the evidence suggesting no or a small effect on mortality and hospital
admission along with a probable increased risk of adverse effects. In light of this evidence, the panel did not anticipate important
variability when it comes to patient values and preferences. In addition, the panel decided that contextual factors such as resources,
feasibility, acceptability and equity for countries and health care systems were unlikely to alter the recommendation. The panel
acknowledged that a strong recommendation against hydroxychloroquine to prevent COVID-19 indicates that this area is no longer a
research priority and that resources should rather be oriented to evaluate other more promising prophylactic interventions.
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Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
Info Box
This first Drugs to prevent COVID-19: A WHO living guideline makes a strong recommendation against the use of hydroxychloroquine
(1). The guideline was initiated after publication of six trials. Please see above for a summary of the guidance.
This is a living guideline, so the recommendation included here will be updated, and new recommendations will be added on other
prophylactic interventions for COVID-19. The guideline is therefore written, disseminated, and updated in a format and structure
aiming to make it user-friendly and easy to navigate while accommodating for dynamically updated evidence and recommendations,
focusing on what is new while keeping existing recommendations within the guideline.
Please visit the WHO website for the latest version of the guidance (1), also available in the BMJ as Rapid Recommendations (2),
supported by the living NMA on COVID-19 prophylaxis, a major evidence source for the guidelines (3).
This guideline is related to two other WHO living guidelines for COVID-19:
• The Therapeutics and COVID-19: living guideline, published 17 December 2020, which includes recommendations on drugs for
patients with suspected or proven COVID-19 (5).
• The COVID-19 Clinical management: living guidance, published 25 January 2021 and also available on MAGICapp, includes
recommendations on a broad list of topics related to non-pharmacological clinical management of COVID-19 (6).
3. Background
As of 16 February 2021, over 108 million people worldwide have been diagnosed with COVID-19, according to the WHO
dashboard (7). The pandemic has so far claimed more than 2.3 million lives, and many areas of the world are experiencing a
resurgence in cases.
This living guideline responds to emerging evidence from randomized controlled trials (RCTs) on prophylactic interventions for
COVID-19. These interventions aim to prevent the disease developing in those who are free from disease. Interventions could
target whole populations, those at higher risk of becoming infected with SARS-CoV-2 due to their work, social circumstances or a
particular exposure, or target those at higher risk of death and poor outcomes.
There are 2610 registered or ongoing trials investigating various interventions for COVID-19 (see Section 8) (8). This rapidly
evolving evidence landscape requires trustworthy interpretation and expeditious clinical practice guidelines to inform clinicians,
patients, governments, ministries and health administrators.
3.1 What triggered this version of the guideline?
This first version of the Drugs to prevent COVID-19: A WHO living guideline adresses theuse of hydroxychloroquine to prevent
COVID-19. It follows the publication of a systematic review and NMA that pooled data from six trials with 6059 participants who
did not have COVID-19 and received hydroxychloroquine (3, 9-14). Three trials enrolled participants who had a known exposure
to a person with SARS-CoV-2 infection.
In response to the release of trial data, the WHO GDG developed recommendations on hydroxychloroquine, an anti-inflammatory
agent that works through blocking of Toll-like receptors reducing dendritic cell activation. It is used to treat rheumatoid arthritis
and systemic lupus erythematosus. It has an antiviral effect against many viruses in vitro, including SARS-CoV-2, but a clinically
useful antiviral effect has not been shown for any viral infection.
3.2 Who made this guideline?
As detailed in Section 4, the WHO convened a standing GDG with 27 clinical content experts, 4 patient-partners and 1 ethicist,
headed by a clinical chair (Dr Michael Jacobs) and a methods chair (Dr Francois Lamontagne). WHO selected GDG members to
ensure global geographical representation, gender balance, and appropriate technical and clinical expertise. No panel member had
a conflict of interest.
Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
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2. Abbreviations
CI confidence interval
COVID-19 coronavirus disease 2019
GDG guideline development group
GRADE Grading of Recommendations Assessment, Development and Evaluation
MAGIC Magic Evidence Ecosystem Foundation
NMA network meta-analysis
PICO population, intervention, comparator, outcome
RCT randomized controlled trial
WHO World Health Organization
The MAGIC Evidence Ecosystem Foundation (MAGIC) provided methodological experts with high-level expertise in standards and
methods for systematic reviews and guideline development, including GRADE; in addition MAGIC offered innovations in
processes (BMJ Rapid Recommendations) and platforms (MAGICapp) for developing living guidance in user-friendly formats. The
methodological experts were not involved in the formulation of recommendations.
3.3 How to use this guideline?
This is a living guideline from the WHO. Recommendations will be updated, and new recommendations will be added on
other prophylactic interventions for COVID-19.
The guideline is written, disseminated and updated in MAGICapp, with a format and structure aiming to make it user-friendly and
easy to navigate (15). It accommodates dynamic updating of evidence and recommendations that can focus on what is new while
keeping existing recommendations, as appropriate, within the guideline. Section 4 outlines key methodological aspects of the
living guideline process including special considerations relevant to the special area of scientific evaluation of prophylactic
interventions.
The guideline is available here in MAGICapp in online, multilayered formats and via:
• WHO website in PDF format (1)
• WHO Academy App (via AppStore and Google Play)
• BMJ Rapid Recommendations with infographics (2)
The purpose of the MAGICapp online formats and additional tools, such as the infographics, is to make it easier to navigate and
make use of the guideline in busy clinical practice. The online multilayered formats are designed to allow end-users to find
recommendations first and then drill down to find supporting evidence and other information pertinent to applying the
recommendations in practice, including tools for shared decision-making (clinical encounter decision aids) (15).
Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
4. Methods: how this guideline was created
The Drugs to prevent COVID-19: A WHO living guideline isdeveloped according to standards and methods for trustworthy guidelines,
making use of an innovative process to achieve efficiency in dynamic updating of recommendations (1). The methods are aligned with
the WHO Handbook for guideline development and according to a pre-approved protocol (planning proposal) by the WHO Guideline
Review Committee (16).
Related guidelines
This guideline is related to the Therapeutics and COVID-19: living guideline , published 17 December 2020, which includes
recommendations on drugs for patients with suspected or proven COVID-19 (5, 17).
The COVID-19 Clinical management: living guidance, published 25 January 2021 and available also on the MAGICapp includes
recommendations on a broad list of topics related to non-pharmacological clinical management of COVID-19 (6).
Timing
This guidance aims to be trustworthy and living; dynamically updated and globally disseminated once new evidence warrants a change
in recommendations for COVID-19 prophylactic interventions. We aim for an ambitious timeframe from trials that trigger guideline
development process to WHO publication, within 1 month, while maintaining standards and methods for trustworthy guidelines
(WHO Handbook for guideline development) (16, 18).
Stepwise approach
Here we outline the stepwise approach we take to improve efficiency and timeliness of the living, trustworthy guidance, in the
development and dissemination of the recommendations. To do so, various processes occurred simultaneously.
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• likelihood to change practice;
• sufficient RCT data on prophylactic interventions to inform the high-quality evidence synthesis living systematic review;
• relevance to a global audience.
Step 2: Convening the GDG
The pre-selected expert panel (see Section 9) convened on two occasions. The first meeting, held on 14 January 2021, focused on
development of clinical questions in PICO formats, prioritization of patient-important outcomes and proposed subgroup analyses. The
second meeting, held on 21 January 2021, served to clarify methodological concepts relevant to guidelines for prophylactic
interventions before reviewing the evidence summary from the living NMA and creating a recommendation for hydroxychloroquine. No
conflict of interest was identified for any panel member according to WHO standards, with individual biographies available on the WHO
website (web link).
Step 3: Evidence synthesis
Following a request by the WHO Therapeutics Steering Committee and coordinated by the Guidance Support Collaboration Committee,
the living systematic review team conducted an independent systematic review and NMA to evaluate prophylactic interventions for
COVID-19. The systematic review team is multidisciplinary and made up of systematic review experts, clinical experts, clinical
epidemiologistsg and biostatisticians. The team has expertise in GRADE methodology and rating certainty of evidence specifically in
NMAs. The NMA team was informed of the deliberations from the initial GDG meeting in order to guide the NMA, specifically focusing
on the outcomes and subgroups prioritized by the panel.
Step 4: Final recommendation
The GRADE approach provided the framework for establishing evidence certainty and generating both the direction and strength of
recommendations (19, 20). Voting procedures were established at the outset, in case consensus was not reached, but these procedures
were not necessary for this recommendation which reached consensus amongst the panel. A simple majority would provide the
direction of the recommendation and 80% would be required to make a strong recommendation.
The following key factors were used to formulate transparent and trustworthy recommendations:
• absolute benefits and harms for all critically important outcomes through structured evidence summaries (e.g. GRADE summary of
findings tables) (21);
• quality/certainty of the evidence (19, 22);
• values and preferences of patients (23);
• resources and other considerations (including considerations of feasibility, applicability, equity) (23);
• for each outcome, effect estimates and confidence intervals, with a measure of certainty in the evidence, were presented in
summary of findings tables;
• recommendations were rated as either conditional or strong, as defined by GRADE (if the panel members disagree regarding the
evidence assessment or strength of recommendations, voting occurs according to established methods).
Step 5: External and internal review
The WHO guideline was then reviewed by pre-specified external reviewers (see Section 9) and then approved by the WHO Guideline
Review Committee.
Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
Step 1: Evidence monitoring and mapping and triggering of evidence synthesis
Comprehensive daily monitoring of all emerging RCTs occurs on a continuous basis, within the context of the living systematic review
and NMA, using experienced information specialists, who look at all relevant information sources for new RCTs addressing interventions
for the prevention of COVID-19. Once practice-changing evidence is identified, the WHO Therapeutics Steering Committee triggers the
guideline development process. With the Guidance Support Collaboration Committee (see Section 9), PICO development and
construction of evidence summaries addressing the intervention of interest are initiated.
The trigger for producing or updating specific recommendations is based on the following:
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Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
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4.1 Special methodological considerations for recommendations on prophylactic
interventions
Implications of very low event rates
Prophylactic interventions are administered to prevent the occurrence of an illness among individuals who are not yet sick. A
minority will develop the illness and, of those, a minority will develop complications from the illness. Accordingly, the number of
critically important events (e.g. death) in studies evaluating prophylactic interventions is typically very low. For that reason,
researchers may choose to measure the effectiveness of prophylactic interventions by measuring their impact on outcomes that are
more common albeit less critically important for patients, such as the development of the illness. In those instances, a more practical
outcome is chosen because it is considered a surrogate for a critically important outcome. For example, if a study yielded evidence
suggesting that an intervention reduces the risk of developing COVID-19, it is plausible that the same intervention would also
reduce the risk of death from COVID-19. However, this would be less certain than if the study had measured mortality directly and
would justify downgrading for indirectness.
What is the guideline panel rating concerning certainty of evidence?
When rating certainty of the evidence for an individual outcome with GRADE, the panel is rating how certain we are that the true
effect lies within a particular range or on one side of a threshold. If there are no serious concerns about risk of bias, inconsistency,
indirectness, or publication bias, the confidence interval will represent a reasonable estimate of a certainty range, that is the range of
reasonably believable effects of the intervention. Guideline panels and guideline users may consider that the same range of plausible
treatment (e.g. 95% CI from 5 fewer to 5 more events per 1000) is highly precise if the panel's focus is to exclude a large treatment
effect corresponding, say, to a reduction of 20 or more events per 1000 individuals, but not precise enough to exclude any effect at
all. The panel's focus depends on what audiences would find most useful. If the focus is on whether there is any effect at all (i.e. a
non-null effect) guidelines may be minimally contextualized; however, if the focus is on the magnitude of effect (i.e. trivial, small,
moderate or large), then the panel's approach must be contextualized (see below).
Contextualization in these guidelines
Given the low event rates in studies evaluating prophylactic interventions (discussed above), a large number of healthy individuals
would have to take a prophylactic medication, and therefore expose themselves to risks and other disadvantages, to prevent one
event from occurring. Accordingly, the panel opted for a partially contextualized approach whereby certainty will be rated for a
magnitude of effect (e.g. trivial, small, moderate, or large effect). Here, the panel is responsible for balancing the magnitude of a
plausible effect that justifies delivering prophylactic interventions in light of the disadvantages associated with treating a very large
number of otherwise healthy individuals.
Subgroup comparisons for evidence pertaining to prophylactic interventions
When evaluating the effect of an intervention, guideline panels examine its absolute effects on critically important outcomes, which
is calculated by multiplying a risk ratio with a population's baseline risk. When ascertaining whether subgroup effects exist, guideline
panels may first look for differences in relative effects between subgroups. An intervention that increases the risk of an event in one
subgroup but reduces the risk in another subgroup is an example of a relative subgroup effect. When evaluating the credibility of
subgroup effects, the WHO panel applied pre-specified criteria (24). For guidelines on prophylactic interventions, the panel chose
to systematically conduct two default subgroup analyses in search of potential differences in relative effects. For the outcome of
laboratory-confirmed infection, the panel examined whether the effect of prophylactic interventions varied as a function of a known
exposure to a person with SARS-CoV-2 infection (as opposed to no known exposure). They also examined if the effect on adverse
events leading to discontinuation of the drug varies as a function of the dose. Additional subgroup analyses looking for differences
in relative effects may be requested a priori by the panel in updates of this living guideline, for other prophylactic interventions.
Whether or not differences in relative effects exist, the effect of a beneficial intervention may vary considerably in absolute terms
across subgroups. This is particularly true of prophylactic interventions since their impact on critically important outcomes depends
on an individual's risk both of developing the illness and of a critically important outcome if ill.
Assuming there is no difference in relative effects, this approach entails modelling the absolute risk of laboratory-confirmed
infection in at least two populations with different baseline risks of developing COVID-19 and then, in each stratum, modelling the
risk of experiencing a critically important outcome in at least two populations with different risks of having that particular outcome.
Fig. 1 illustrates how this modelling may result in different absolute risks of experiencing a critically important outcome after
prophylaxis.
Fig. 1. Determination of varying absolute risks of critically important outcomes based on modelling
5. The latest evidence
This section outlines what information the GDG panel requested and used in making their recommendation for hydroxychloroquine
prophylaxis.
Benefits and harms
The GDG panel requested an update of the living NMA of RCTs of prophylactic interventions for COVID-19.
The GDG members prioritized outcomes (rating from 1 [not important] to 9 [critical]) taking a patient's perspective (Table 1). The panel’s
questions were structured using the PICO format (see evidence profile under the recommendations).
Table 1. Panel outcome rating from a patient perspective
Outcome Min Max Median Mean SD
Death 3 9 9 8.4 1.55
Infection (lab-confirmed) 2 9 7 6.74 1.84
Infection (suspected or probable, or
lab-confirmed)
1 9 6 5.95 2.14
Admission to hospital 5 9 7.5 7.35 1.11
Adverse effects leading to
discontinuation
2 9 7 6.75 1.56
Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
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Note: The asterisk (*) in the final column refers to multiplication.
Time to resolution or clinical
improvement
3 9 5 5 1.73
SD = Standard deviation.
Note: 1: not important, 9: critically important.
Geographic regions
North America
Europe
Asia
Middle East
South America
Australasia
4 trials, 3265 participants
2 trials, 2794 participants
0 trials, 0 patients
Exposure to the virus
Known exposure
No known exposure
3 trials, 4175 participants
3 trials, 1884 participants
Age Mean age (range of means) 43.6 (33–48.7)
Sex Mean % of men (range of means) 37.2 (26.8–48.8)
Dose on day 1
Mean dose on day 1 in mg (range of
means)
706.6 (400–1400)
Total cumulative dose
Median cumulative dose in mg (range of
cumulative dose)
5200 (3200–33 600)
Duration of therapy Median number of days (range) 35 (5–172)
Type of risk
Close contact
Healthcare workers (considered without a
known exposure)
3 trials, 4175 participants
3 trials, 1884 participants
Number of participants Median, range 825 (132–2525)
Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
For hydroxychloroquine, the evidence summary was based on six trials and 6059 participants for which the NMA provided relative
estimates of effect for patient-important outcomes (9-14) (Table 2). Three trials enrolled participants who had a known exposure to a
person with SARS-CoV-2 infection and three others enrolled participants without a known exposure.
Table 2. Summary of trial characteristics informing the hydroxychloroquine recommendation (trials = 6, total patients = 6059)
Subgroup analyses
The GDG requested subgroup analyses based on known vs. unknown exposure to a person with SARS-CoV-2 infection and
hydroxychloroquine dosing regimen.
The panel discussed the relevance of seeking potential subgroup effects for all outcomes but recognized that these analyses would not
be possible for mortality given the extremely low number of deaths in studies evaluating prophylactic interventions.
The pairwise subgroup analyses were performed using a Bayesian analysis which incorporated meta-regression using study as a
random effect. The panel used a pre-specified framework incorporating the ICEMAN tool to assess the credibility of subgroup
findings (24). With evidence summaries showing moderate to high certainty of no important benefit for hydroxychloroquine in any
subgroup on any outcome, the panel decided not to stratify patients based on differing baseline risks for the patient-important
outcomes.
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• Mortality would be the outcome most important to individuals, followed by need for hospital admission, laboratory-confirmed
COVID-19, and adverse effects leading to discontinuation.
• Most individuals would be reluctant to use a medication for which the evidence left high uncertainty regarding effects on the
outcomes listed above, particularly when evidence suggested treatment effects, if they do exist, are small, and the possibility of
important harm remains.
The panel acknowledged, however, that values and preferences are likely to vary. There will be individuals inclined to use a
prophylactic intervention when an important benefit cannot be ruled out, particularly when the underlying condition is potentially fatal.
On the other hand, other individuals will have a high threshold of likely benefit before opting to take medications prophylactically.
Although the panel focused on an individual patient perspective, the members also considered a population perspective in which
feasibility, acceptability, equity and cost are important considerations, particularly when a very large number of otherwise healthy
individuals might need to be treated before preventing one outcome.
6. Who do the recommendations apply to?
Info Box
This Drugs to prevent COVID-19: A WHO living guideline applies to all individuals who do not have COVID-19.
In the case of hydroxychloroquine, the GDG concluded that there was no justification for any specific recommendations for
individuals with known exposure to a person with SARS-CoV2 infection, or for different drug doses.
Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
Baseline risk estimates (prognosis of patients with COVID-19): informing absolute estimates of effect
The baseline risks were calculated from data from the control groups of trials included in the NMA, which also yielded the estimate
of relative effects of prophylactic interventions (3). The evidence summaries that informed the guideline recommendation reported
the anticipated absolute effects of hydroxychloroquine compared with usual care across all patient-important outcomes, with explicit
judgments of certainty in the evidence for each outcome. For mortality, the event rate among all participants randomized to standard
care or placebo was used to calculate the baseline risk. For all other outcomes, the median event rate in the standard care or placebo
arms was used, with each study weighted equally.
Values and preferences
There were insufficient published data to provide the panel with an informative systematic review of studies describing individuals'
experiences or values and preferences on treatment decisions for COVID-19 prophylactic interventions. The panel members
therefore relied on their own judgments of what well-informed individuals would value after carefully balancing the benefits, harms
and burdens of prophylactic interventions and their subsequent preferences. The panel included four patient-representatives who
had lived experience with COVID-19.
The panel agreed that the following values and preferences would be representative of those of typical well-informed patients:
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7. Recommendations for prophylaxis
7.1 Hydroxychloroquine
Evidence to decision
Justification
When moving from the evidence to the strong recommendation against the use of hydroxychloroquine to prevent COVID-19,
the panel emphasized the evidence suggesting no or a small effect on mortality and hospital admission along with a probable
increased risk of adverse effects. In light of this evidence, the panel did not anticipate important variability when it comes to
patient values and preferences. In addition, the panel decided that contextual factors such as resources, feasibility, acceptability
and equity for countries and health care systems were unlikely to alter the recommendation. The panel acknowledged that a
strong recommendation against hydroxychloroquine to prevent COVID-19 indicates that this area is no longer a research
priority and that resources devoted to clinical research should rather be oriented to evaluate other more promising prophylactic
interventions.
Recommendation against
We recommend against administering hydroxychloroquine prophylaxis to individuals who do not have COVID-19 (strong
recommendation, high certainty evidence).
Remark: This recommendation applies to individuals with any baseline risk of developing COVID-19 and any hydroxychloroquine dosing
regimen.
New
Used prophylactically, hydroxychloroquine has a small or no effect on death and hospital admission (high certainty), and
probably has a small or no effect on laboratory-confirmed COVID-19 (moderate certainty). It probably increases the risk of
adverse effects leading to discontinuation of the drug (moderate certainty).
There was no subgroup effect according to known exposure to a person with SARS-CoV-2 infection or hydroxychrloroquine
dose regimen (extremely low event rates precluded investigation of subgroup effects for mortality). The panel therefore
assumed similar relative effects across subgroups.
Substantial net benefits of the recommended alternativeBenefits and harms
For key outcomes of mortality and hospital admission, the panel had high certainty that hydroxychloroquine had no or a
small effect. The certainty was moderate for the outcome of laboratory-confirmed COVID-19 due to serious risk of bias
(lack of blinding in one trial), and also for adverse effects due to serious imprecision (in this case the panel assessed the
certainty that the null effect could be excluded).
HighCertainty of the Evidence
Given the evidence, the panel inferred that almost all well-informed individuals would decline hydroxychloroquine.
We expect few to want the interventionPreference and values
Hydroxychloroquine is relatively inexpensive and is widely available, including in low-income settings. Although the cost
may be low per patient, the overall cost of delivering a prophylactic intervention on a large scale may be significant.
Moreover, the panel raised concerns about diverting hydroxychloroquine stocks away from patients with other
conditions for whom this medication is indicated (25).
Important negative issuesResources and other considerations
Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
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Subgroup analyses
The panel did not find any evidence of a subgroup effect as a function of known exposure to infection or by dose of
hydroxychloroquine. Of note, for trials that enrolled participants without a known exposure to infection, the weekly dose of
hydroxychloroquine was used as the variable of interest to account for longer term prophylaxis; for trials that enrolled
participants following a known exposure to infection, the cumulative dose was used as the variable of interest to reflect shorter
term prophylaxis. As no subgroup effect modification was found, the strong recommendation is applicable across risk groups and
dose regimens of hydroxychloroquine.
The trials included participants from North and South America and Europe who either had a known exposure to a person with
SARS-CoV-2 infection or who were considered at risk given their professional occupations (e.g. health care workers).
Applicability
Regarding special populations, none of the included RCTs enrolled children, and therefore the applicability of this
recommendation to children is currently uncertain. However, the panel had no reason to think that children would respond any
differently to prophylactic hydroxychloroquine. There were similar considerations in regards to pregnant women, with no data
directly examining this population, but no rationale to suggest they would respond differently to other adults.
Hydroxychloroquine crosses the placental barrier and there are concerns that it may lead to retinal damage in neonates.
Although hydroxychloroquine has been used in pregnant women with systemic autoimmune diseases, such as systemic lupus
erythematosus, pregnant women may have even more reasons than other individuals to be reluctant to use hydroxychloroquine
for COVID-19 prophylaxis.
Uncertainties
Please see Section 8 for residual uncertainties. The panel felt that it was unlikely future studies would identify a subgroup of
individuals likely to benefit from hydroxychloroquine prophylaxis.
Clinical question/PICO
Population: Individuals who do not have COVID-19
Intervention: Hydroxychloroquine
Comparator: Standard care
Outcome
Timeframe
Study results and
measurements
Absolute effect estimates
Standard care Hydroxychloroquine
Certainty of
the evidence
(Quality of
evidence)
Plain text summary
Mortality
Odds Ratio 0.7
(CI 95% 0.24 - 1.99)
Based on data from
4849 patients in 4
studies. (Randomized
controlled)
Difference: 1 fewer per 1000
( CI 95% 2 fewer - 3 more )
3
per 1000
2
per 1000
High
Hydroxychloroquine has
a small or no effect on
mortality.
Admission to
hospital
Odds Ratio 0.87
(CI 95% 0.42 - 1.77)
Based on data from
5659 patients in 5
studies. (Randomized
controlled)
Difference: 1 fewer per 1000
( CI 95% 3 fewer - 4 more )
5
per 1000
4
per 1000
High
Hydroxychloroquine has
a small or no effect on
hospital admission.
Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
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Outcome
Timeframe
Study results and
measurements
Absolute effect estimates
Standard care Hydroxychloroquine
Certainty of
the evidence
(Quality of
evidence)
Plain text summary
Lab-confirmed
COVID-19
diagnosis
Odds Ratio 1.03
(CI 95% 0.71 - 1.47)
Based on data from
5294 patients in 6
studies.
Difference: 2 more per 1000
( CI 95% 18 fewer - 28 more )
65
per 1000
67
per 1000 Moderate
Due to serious
risk of bias 1
Hydroxychloroquine
probably has a small or
no effect on labconfirmed
COVID-19
diagnosis.
Adverse events
leading to
discontinuation
Odds Ratio 2.34
(CI 95% 0.93 - 6.08)
Based on data from
3616 patients in 4
studies.
Difference: 19 more per 1000
( CI 95% 1 fewer - 70 more )
15
per 1000
34
per 1000 Moderate
Due to serious
imprecision 2
Hydroxychloroquine
probably increases
adverse events leading
to discontinuation.
Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
8. Uncertainties, emerging evidence and future research
Ongoing uncertainties and opportunities for future research
Hydroxychloroquine
The panel felt that further research was unlikely to uncover a subgroup of patients that benefit from hydroxychloroquine prophylaxis
on the most important outcomes (mortality, admission to hospital, laboratory-confirmed COVID-19) given the consistent results in
trials across subgroups and location.
Emerging evidence
The unprecedented volume of planned and ongoing studies for COVID-19 interventions (2610 randomized controlled trials as of 18
February 2021) implies that further evidence will emerge to inform policy and practice. An overview of registered and ongoing trials
for COVID-19 therapeutics and prophylaxis is available from the Infectious Diseases Data Observatory, through their living systematic
review of COVID-19 clinical trial registrations, the WHO website and other repositories, such as the COVID-NMA initiative (8).
Concerning hydroxychloroquine or chloroquine prophylaxis, more than 80 trials planning to enroll at least 100 000 participants are
registered or ongoing (8). The high certainty evidence that has emerged regarding the lack of effect of hydroxychloroquine prophylaxis
suggests that funders and researchers should reconsider the initiation or continuation of these trials.
9. Authorship, contributions and acknowledgements
WHO would like to thank the collaborative efforts of all those involved to make this process rapid, efficient, trustworthy and
transparent, including extensive in-kind support from the Magic Evidence Ecosystem Foundation (MAGIC) and their partner, the BMJ,
to develop and disseminate this living guideline for prevention of COVID-19, based on a living systematic review and network analysis
from investigators at McMaster University, Canada.
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WHO Therapeutics Steering Committee
The committee includes representatives from various WHO departments at headquarters and the regions and has been approved by
the WHO Director of the Country Readiness Department, and the WHO Chief Scientist. The WHO Secretariat meets on a regular basis
to discuss when to trigger guideline updates based on evidence updates from the WHO Rapid Review Team, and other sources of
evidence and selects the members of the Guideline Development Group (GDG).
Janet V Diaz (Lead, Clinical Team for COVID-19 Response, Health Emergencies Programme, Geneva); John Appiah (Lead, case
management, WHO Regional Office for Africa); Lisa Askie (Quality Assurance of Norms and Standards Department); Silvia Bertagnolio
(Communicable and Noncommunicable Diseases Division/Clinical Team for COVID-19 Response); Nedret Emiroglu (Country Readiness
Strengthening, Health Emergencies Programme); John Grove (Quality Assurance of Norms and Standards Department); Rok Ho Kim
(Quality Assurance of Norms and Standards Department); Chiori Kodama (WHO Regional Office for the Eastern Mediterranean);
Lorenzo Moja (Health Products Policy and Standards Department); Olufemi Oladapo (Sexual and Reproductive Health and Research
Department); Dina Pfeifer (WHO Regional Office for Europe/Health Emergencies Programme); Jacobus Preller (Clinical Team for
COVID-19 Response); Pryanka Relan (Integrated Health Services Department/Clinical Team for COVID-19 Response); Ludovic Reveiz
(Evidence and Intelligence for Action in Health Department, Incident Management Systems for COVID-19, Pan American Health
Organization); Soumya Swaminathan (Office of Chief Scientist); Wilson Were (Maternal, Newborn, Child and Adolescent Health and
Ageing Department); Pushpa Wijesinghe (Lead, case management, Regional Office for South-East Asia). Supporting project officer:
Jacqueline Lee Endt (Health Care Readiness Unit, Health Emergencies Programme).
The WHO Therapeutics Steering Committee is fully responsible for decisions about guideline production and convening the GDG.
We would like to acknowledge the Guidance Support Collaboration Committee which provided the coordination between WHO and
MAGIC to allow the rapid development of the WHO guideline and its dissemination: Thomas Agoritsas (MAGIC, University Hospitals of
Geneva); Janet Diaz (WHO); Fiona Godlee (BMJ); Gordon H Guyatt (McMaster University, Canada); Navjoyt Ladher (BMJ); Francois
Lamontagne (Université de Sherbrooke, Canada); Srinivas Murthy (University of British Columbia, Canada); Bram Rochwerg (McMaster
University, Canada); Per Olav Vandvik (MAGIC, University of Oslo, Norway). Though members of this group represent various
stakeholders in the process of development and dissemination of the WHO guideline, the roles of each stakeholder were transparent
and kept independent and thus these sessions used to share updates and enhance coordination.
Guideline Development Group (GDG)
Wagdy Amin (Ministry of Health and Population, Egypt); Frederique Bausch (Geneva University Hospital, Switzerland); Erlina Burhan
(Infection Division, Department of Pulmonology and Respiratory Medicine, Faculty of Medicine, Universitas Indonesia); Maurizio
Cecconi (Humanitas Research Hospital, Milan, Italy); Duncan Chanda (Adult Infectious Disease Centre, University Teaching Hospital,
Lusaka, Zambia); Vu Quoc Dat (Department of Infectious Diseases, Hanoi Medical University, Hanoi, Viet Nam); Bin Du (Peking Union
Medical College Hospital, China); Heike Geduld (Emergency Medicine, Stellenbosch University, South Africa); Patrick Gee (patient panel
member, United States of America); Nerina Harley (Royal Melbourne Hospital, Melbourne, Australia); Madiha Hashmi (Ziauddin
University, Karachi, Pakistan); Manai Hela (Emergency Medical Service Tunis, Tunisia); Beverley Hunt (Guy’s and St Thomas’ NHS
Foundation Trust, London, United Kingdom); Sushil Kumar Kabra (All India Institute of Medical Sciences, New Delhi, India); Seema
Kanda (patient panel member, Ontario, Canada); Leticia Kawano-Dourado (Research Institute, Hospital do Coração, São Paulo, Brazil);
Yae-Jean Kim (Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul, Republic of Korea); Niranjan Kissoon
(Department of Paediatrics and Emergency Medicine, University of British Columbia, Vancouver, Canada); Arthur Kwizera (Makerere
College of Health Sciences, Kampala, Uganda); Leo Yee-Sin (National Centre for Infectious Diseases, Singapore); Imelda Mahaka (patient
panel member, Pangaea Harare, Zimbabwe); Greta Mino (Alcivar Hospital, Guayaquil, Ecuador); Emmanuel Nsutebu (Sheikh Shakhbout
Medical City, Abu Dhabi); Natalia Pshenichnaya (Central Research Institute of Epidemiology of Rospotrebnadzor, Moscow, Russian
Federation); Nida Qadir (Pulmonary and Critical Care Medicine, David Geffen School of Medicine, University of California, Los Angeles,
United States of America); Saniya Sabzwari (Aga Khan University, Karachi, Pakistan); Rohit Sarin (National Institute of Tuberculosis and
Respiratory Diseases, New Delhi, India); Michael Sharland (St George’s University, London, United Kingdom); Yinzhong Shen (Shanghai
Public Health Clinical Center, Fudan University, Shanghai, China); Shalini Sri Ranganathan (University of Colombo, Sri Lanka); Joao Paulo
Souza (University of São Paulo, Brazil); Miriam Stegemann (Charite, Berlin, Germany); Sebastian Ugarte (Faculty of Medicine, Andres
Bello University, Indisa Clinic, Santiago, Chile); Sridhar Venkatapuram (King’s College London, United Kingdom); Dubula Vuyiseka
(patient panel member, University of Stellenbosch, South Africa).
Methods Chair
Francois Lamontagne (Université de Sherbrooke, Canada).
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Drugs to prevent COVID-19: A WHO living guideline - World Health Organization (WHO)
Clinical Chair
Michael Jacobs (Royal Free London NHS Foundation Trust, United Kingdom).
Methods resource persons
Arnav Agarwal (University of Toronto, Canada); Thomas Agoritsas; Romina Brignardello-Petersen (McMaster University, Canada);
Gordon H Guyatt (McMaster University, Canada); George Tomlinson (Department of Medicine, University Health Network, Toronto,
Canada); Per Olav Vandvik; Linan Zeng (West China Second University Hospital, Sichuan University, Chengdu, China; McMaster
University, Canada).
No conflict of interest was identified for any member. For members involved in the living systematic review see next paragraph. For
MAGIC members, all completed WHO conflict of interest forms and also BMJ forms for their co-authorship in the guideline appearing
in the BMJ (2).
Living systematic review/NMA team
Arnav Agarwal; Thomas Agoritsas; Jessica J Bartoszko (McMaster University, Canada); Romina Brignardello-Petersen; Derek K Chu
(McMaster University, Canada); Rachel Couban (McMaster University, Canada); Andrea Darzi (McMaster University, Canada); Tahira
Devji (McMaster University, Canada); Bo Fang (Chongqing Medical University, Chongqing, China); Carmen Fang (William Osler Health
Network, Toronto, Canada); Signe Agnes Flottorp (Institute of Health and Society, University of Oslo, Norway); Farid Foroutan
(McMaster University, Canada); Long Ge (School of Public Health, Lanzhou University, Gansu, China); Gordon H Guyatt; Mi Ah Han
(College of Medicine, Chosun University, Gwangju, Republic of Korea); Diane Heels-Ansdell (McMaster University, Canada); Kimia
Honarmand (Department of Medicine, Western University, London, Canada); Liangying Hou (School of Public Health, Lanzhou
University, Gansu, China); Xiaorong Hou (Chongqing Medical University, Chongqing, China); Quazi Ibrahim (McMaster University,
Canada); Ariel Izcovich (Servicio de Clinica Médica del Hospital Alemán, Buenos Aires, Argentina); Elena Kum (McMaster University,
Canada); Francois Lamontagne; Qin Liu (School of Public Health and Management, Chongqing Medical University, Chongqing, China);
Mark Loeb (McMaster University, Canada); Maura Marcucci (McMaster University, Canada); Shelley L McLeod (Schwartz/Reisman
Emergency Medicine Institute, Sinai Health, Toronto, Canada); Shahrzad Motaghi, (McMaster University, Canada); Srinivas Murthy;
Reem A Mustafa (McMaster University, Canada); John D Neary (McMaster University, Canada); Hector Pardo-Hernandez
(Iberoamerican Cochrane Centre, Sant Pau Biomedical Research Institute [IIB Sant Pau], Barcelona, Spain); Anila Qasim (McMaster
University, Canada); Gabriel Rada (Epistemonikos Foundation, Santiago, Chile); Irbaz Bin Riaz (Hematology and Oncology, Mayo Clinic
Rochester, Rochester, United States of America); Bram Rochwerg, Behnam Sadeghirad (McMaster University, Canada); Nigar
Sekercioglu (McMaster University, Canada); Lulu Sheng (School of Public Health and Management, Chongqing Medical University,
Chongqing, China); Reed AC Siemieniuk (McMaster University, Canada); Ashwini Sreekanta (McMaster University, Canada);
Charlotte Switzer (McMaster University, Canada); Britta Tendal (School of Public Health and Preventative Medicine, Monash University,
Melbourne, Australia); Lehana Thabane (McMaster University, Canada); George Tomlinson; Tari Turner (School of Public Health and
Preventative Medicine, Monash University, Melbourne, Australia); Per Olav Vandvik; Robin WM Vernooij (Department of Nephrology
and Hypertension, University Medical Center Utrecht, Netherlands); Andrés Viteri-García (Epistemonikos Foundation, Santiago, Chile);
Ying Wang (McMaster University, Canada); Liang Yao (McMaster University, Canada); Zhikang Ye (McMaster University, Canada); Dena
Zeraatkar (McMaster University, Canada).
No conflict of interest was identified for any member, as reported in the ICMJE disclosure forms completed for the submission of the
manuscript to BMJ (in peer-review, published at MedRxiv) (3).
External reviewers
Special thanks are extended to the external reviewers for their insights: Yaseen Arabi (King Saud Bin Abdulaziz University for Health
Sciences, Saudi Arabia); Richard Kojan (Alliance for International Medical Action); Bhargavir Rao (Médecins Sans Frontières).
No conflict of interest was identified for the external reviewers, based on completed WHO declaration forms.
Infographic
Special thanks to the BMJ for providing the infographic for this guideline.
Funding
No specific funding was provided for this guideline, with MAGIC providing pro bono contributions and support to WHO in the context
of the COVID-19 pandemic.
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