Summary of COVID-19 PPE studies
Studies
Meta Analysis
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RCT 342,183 adults in Bangladesh showing lower COVID-19 cases with a community-level mask promotion and distribution intervention. The reduction in symptoms and seroprevalence was larger with surgical masks compared to cloth masks, and in older adults. Villages were randomly assigned to receive free cloth or surgical masks along with education and promotion of mask-wearing, or no intervention. Author do not report any information on the severity of cases.
Jan 2022, Science, https://www.science.org/doi/10.1126/science.abi9069, https://c19p.org/abaluck
RCT 4,862 community-dwelling adults in Denmark, showig no significant difference in COVID-19 cases with recommending the use of surgical masks outside the home. The prespecified mortality outcomes are not reported and the only severity information provided is symptom counts.
Nov 2020, Annals of Internal Medicine , https://www.acpjournals.org/doi/10.7326/M20-6817, https://c19p.org/bundgaard
RCT 4,575 adults in Norway showing no significant difference in reported COVID-19 cases with surgical face mask use in public spaces. The study reports lower risk of overall respiratory infections, however this may be due to reporting bias - many more patients did not report data in the intervention arm, and the intervention appeared to be much more successful in patients with the belief that masks reduce infection (Figure 2), i.e., patients in the mask group that believe masks work may be less likely to report failure of their belief. In theory, if the missing data for intervention patients is more likely to show infection, imputation using the baseline predictors would adjust the odds ratio upward, however only mask belief shows a significant association with the outcome, and the analysis cannot distinguish between an actual association and reporting bias.
Jul 2024, BMJ, https://www.bmj.com/lookup/doi/10.1136/bmj-2023-078918, https://c19p.org/solberg
245 patient PPE prophylaxis RCT: 98% more cases (p=0.06) and 164% worse results (p=0.08).
Cluster RCT 81 index cases and 245 household contacts in South Africa, showing no significant difference in COVID-19 cases with PPE use. The only symptom information is reported for index cases in the registry under adverse events. Publication was delayed for close to 3 years without explanation. Results were submitted to clinicaltrials.gov in 2022 but not made available until 2024.
Jul 2024, BMC Public Health, https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-024-19462-1, https://c19p.org/smith4
1. Abaluck et al., Impact of community masking on COVID-19: A cluster-randomized trial in Bangladesh
342,183 patient PPE prophylaxis RCT: 9% fewer symptomatic cases (p=0.05).RCT 342,183 adults in Bangladesh showing lower COVID-19 cases with a community-level mask promotion and distribution intervention. The reduction in symptoms and seroprevalence was larger with surgical masks compared to cloth masks, and in older adults. Villages were randomly assigned to receive free cloth or surgical masks along with education and promotion of mask-wearing, or no intervention. Author do not report any information on the severity of cases.
Jan 2022, Science, https://www.science.org/doi/10.1126/science.abi9069, https://c19p.org/abaluck
2. Bundgaard et al., Effectiveness of Adding a Mask Recommendation to Other Public Health Measures to Prevent SARS-CoV-2 Infection in Danish Mask Wearers
4,862 patient PPE prophylaxis RCT: 18% fewer cases (p=0.33).RCT 4,862 community-dwelling adults in Denmark, showig no significant difference in COVID-19 cases with recommending the use of surgical masks outside the home. The prespecified mortality outcomes are not reported and the only severity information provided is symptom counts.
Nov 2020, Annals of Internal Medicine , https://www.acpjournals.org/doi/10.7326/M20-6817, https://c19p.org/bundgaard
3. Solberg et al., Personal protective effect of wearing surgical face masks in public spaces on self-reported respiratory symptoms in adults: pragmatic randomised superiority trial
3,801 patient PPE prophylaxis RCT: 7% more cases (p=0.82).RCT 4,575 adults in Norway showing no significant difference in reported COVID-19 cases with surgical face mask use in public spaces. The study reports lower risk of overall respiratory infections, however this may be due to reporting bias - many more patients did not report data in the intervention arm, and the intervention appeared to be much more successful in patients with the belief that masks reduce infection (Figure 2), i.e., patients in the mask group that believe masks work may be less likely to report failure of their belief. In theory, if the missing data for intervention patients is more likely to show infection, imputation using the baseline predictors would adjust the odds ratio upward, however only mask belief shows a significant association with the outcome, and the analysis cannot distinguish between an actual association and reporting bias.
Jul 2024, BMJ, https://www.bmj.com/lookup/doi/10.1136/bmj-2023-078918, https://c19p.org/solberg
245 patient PPE prophylaxis RCT: 98% more cases (p=0.06) and 164% worse results (p=0.08).
Cluster RCT 81 index cases and 245 household contacts in South Africa, showing no significant difference in COVID-19 cases with PPE use. The only symptom information is reported for index cases in the registry under adverse events. Publication was delayed for close to 3 years without explanation. Results were submitted to clinicaltrials.gov in 2022 but not made available until 2024.
Jul 2024, BMC Public Health, https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-024-19462-1, https://c19p.org/smith4
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