Abstract
BackgroundIn this large-scale cluster-randomized controlled trial (cRCT) we sought to assess the effectiveness of facemasks against viral respiratory infections.Methods and resultsOver three consecutive Hajj seasons (2013, 2014, 2015) pilgrims’ tents in Makkah were allocated to ‘facemask’ or ‘no facemask’ group. Fifty facemasks were offered to participants in intervention tents, to be worn over four days, and none were offered to participants in control tents. All participants recorded facemask use and respiratory symptoms in health diaries. Nasal swabs were collected from the symptomatic for virus detection by reverse transcription polymerase chain reaction. Clinical symptoms and laboratory results were analyzed by ‘intention- to-treat’ and ‘per-protocol’. A total of 7687 adult participants from 318 tents were randomized: 3864 from 149 tents to the intervention group, and 3823 from 169 tents to the control group. Participants were aged 18 to 95 (median 34, mean 37) years, with a male to female ratio of 1:1.2. Overall, respiratory viruses were detected in 277 of 650 (43%) nasal/pharyngeal swabs collected from symptomatic pilgrims. Common viruses were rhinovirus (35.1%), influenza (4.5%) and parainfluenza (1.7%). In the intervention arm, respectively 954 (24.7%) and 1842 (47.7%) participants used facemasks daily and intermittently, while in the control arm, respectively 546 (14.3%) and 1334 (34.9%) used facemasks daily and intermittently. By intention-to-treat analysis, facemask use did not seem to be effective against laboratory-confirmed viral respiratory infections (odds ratio [OR], 1.4; 95% confidence interval [CI], 0.9 to 2.1, p = 0.18) nor against clinical respiratory infection (OR, 1.1; 95% CI, 0.9 to 1.4, p = 0.40). Similarly, in a per-protocol analysis, facemask use did not seem to be effective against laboratory-confirmed viral respiratory infections (OR 1.2, 95% CI 0.9–1.7, p = 0.26) nor against clinical respiratory infection (OR 1.3, 95% CI 1.0–1.8, p = 0.06).ConclusionThis trial was unable to provide conclusive evidence on facemask efficacy against viral respiratory infections most likely due to poor adherence to protocol.
Highlights
Viral respiratory infections are a major public health burden, causing serious disease especially in vulnerable populations
By intention-to-treat analysis, facemask use did not seem to be effective against laboratory-confirmed viral respiratory infections nor against clinical respiratory infection (OR, 1.1; 95% confidence intervals (CIs), 0.9 to 1.4, p = 0.40)
Following the Consolidated Standards of Reporting Trials (CONSORT) guidelines (S1 Checklist) for cluster-randomized controlled trial (cRCT) participants in respective tents were allocated to intervention or control group as per the trial protocol (S2 Appendix) [20, 21]
Summary
Viral respiratory infections are a major public health burden, causing serious disease especially in vulnerable populations. Coming from over 180 countries pilgrims converge on Makkah to join a procession of two to three million people who perform a series of physically demanding rituals. Such religious and other mass gatherings amplify the transmission of respiratory viruses by up to eight times [3] and may even accelerate the progression of a pandemic as occurred during the 2009 influenza A (H1N1) pandemic following the Iztapalapa Passion Play mass gathering in Mexico in April 2009 [4]. The current outbreak of coronavirus disease 2019 (COVID-19) is an example of how travel accelerates the spread of respiratory viral infection [5]. In this large-scale cluster-randomized controlled trial (cRCT) we sought to assess the effectiveness of facemasks against viral respiratory infections
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