Prophylaxis against covid-19: living systematic review and network meta-analysis

source extracted confidence: high 2026-04-09
#anti-infective-agents #covid-19 #carrageenan #chemoprevention #global-health

Prophylaxis against covid-19: living systematic review and network meta-analysis

Bartoszko et al., 2021 | BMJ | Systematic Review

Citation

Bartoszko Jessica J, Siemieniuk Reed A C, ... Brignardello-Petersen Romina. Prophylaxis against covid-19: living systematic review and network meta-analysis. BMJ. 2021-Apr-26;373:n949. doi:10.1136/bmj.n949

Abstract

UPDATES: This is the second version (first update) of the living systematic review, replacing the previous version (available as a data supplement). When citing this paper please consider adding the version number and date of access for clarity. OBJECTIVE: To determine and compare the effects of drug prophylaxis on severe acute respiratory syndrome coronavirus virus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (covid-19). DESIGN: Living systematic review and network meta-analysis (NMA). DATA SOURCES: World Health Organization covid-19 database, a comprehensive multilingual source of global covid-19 literature to 4 March 2022. STUDY SELECTION: Randomised trials in which people at risk of covid-19 were allocated to prophylaxis or no prophylaxis (standard care or placebo). Pairs of reviewers independently screened potentially eligible articles. METHODS: After duplicate data abstraction, we conducted random-effects bayesian network meta-analysis. We assessed risk of bias of the included studies using a modification of the Cochrane risk of bias 2.0 tool and assessed the certainty of the evidence using the grading of recommendations assessment, development and evaluation (GRADE) approach. RESULTS: The second iteration of this living NMA includes 32 randomised trials which enrolled 25 147 participants and addressed 21 different prophylactic drugs; adding 21 trials (66%), 18 162 participants (75%) and 16 (76%) prophylactic drugs. Of the 16 prophylactic drugs analysed, none provided convincing evidence of a reduction in the risk of laboratory confirmed SARS-CoV-2 infection. For admission to hospital and mortality outcomes, no prophylactic drug proved different than standard care or placebo. Hydroxychloroquine and vitamin C combined with zinc probably increase the risk of adverse effects leading to drug discontinuation—risk difference for hydroxychloroquine (RD) 6 more per 1000 (95% credible interval (CrI) 2 more to 10 more); for vitamin C combined with zinc, RD 69 more per 1000 (47 more to 90 more), moderate certainty evidence. CONCLUSIONS: Much of the evidence remains very low certainty and we therefore anticipate future studies evaluating drugs for prophylaxis may change the results for SARS-CoV-2 infection, admission to hospital and mortality outcomes. Both hydroxychloroquine and vitamin C combined with zinc probably increase adverse effects. SYSTEMATIC REVIEW REGISTRATION: This review was not registered. The protocol established a priori is included as a supplement. FUNDING: This study was supported by the Canadian Institutes of Health Research (grant CIHR-IRSC:0579001321).

Key Findings

The second iteration of this living NMA includes 32 randomised trials which enrolled 25 147 participants and addressed 21 different prophylactic drugs; adding 21 trials (66%), 18 162 participants (75%) and 16 (76%) prophylactic drugs. Of the 16 prophylactic drugs analysed, none provided convincing evidence of a reduction in the risk of laboratory confirmed SARS-CoV-2 infection. For admission to hospital and mortality outcomes, no prophylactic drug proved different than standard care or placebo.

Outcomes Measured

  • Requires manual extraction

Population

Field Value
Population See abstract
Sample Size 147
Age Range See abstract
Condition See abstract

MeSH Terms

  • Anti-Infective Agents
  • COVID-19
  • Carrageenan
  • Chemoprevention
  • Global Health
  • Humans
  • Hydroxychloroquine
  • Ivermectin
  • SARS-CoV-2
  • Treatment Outcome
  • Uncertainty

Evidence Classification

  • Level: Systematic Review
  • Publication Types: Journal Article, Research Support, Non-U.S. Gov't, Systematic Review, Network Meta-Analysis
  • Vertical: zinc

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09