Wearing a surgical mask did not protect against Covid-19 as effectively as did a respiratory mask, suggests a study published in JAMA Network Open.

The objective of this study was to find out the impact of the type of mask and level of exposure on the risk of Covid-19 among 2919 health care workers, aged 18-73 years (mean age 43). A little over one-quarter (26%) of the participants had SARS-CoV-2 infection and 13% of the infected health care workers had no history of exposure to a Covid patient.

Among those who were exposed to Covid-19 patients, 21% of the healthcare workers using respirator masks were positive for Covid, whereas this number was 35% among those who used surgical/mixed masks.

On multivariable analysis, exposure to a positive household contact was associated with the highest risk of infection (nearly 8-folds increase) with an odds ratio of 7.79. Expectedly, SARS-CoV-2 vaccination was protective (OR 0.55). Following exposure for 2 to 4 hours, the likelihood of testing positive was 25%. This probability increased to nearly 33% with exposure for 8 to 16 hours and 43% for exposure time of more than 64 hours.

This observational study demonstrates that the type of mask used by the health care workers influenced their risk of acquiring SARS-CoV-2 infection and also stresses on the beneficial effects of Covid-19 vaccines. Those who wore respirators were at a lower risk of infection regardless of the cumulative exposure. Therefore, consistent use of a proper mask (respirators) along with Covid vaccination (primary vaccination plus precaution dose) may reduce the occupational risk of infection among health care workers managing Covid patients, particularly who are at high risk.

Reference

1. Tamara Dörr, et al. Risk of SARS-CoV-2 acquisition in health care workers according to cumulative patient exposure and preferred mask type. JAMA Netw Open. 2022 Aug 1;5(8):e2226816. doi: 10.1001/jamanetworkopen.2022.26816.