Effect of mask use on COVID-19 positivity rates in HCWs

Editor's Note

This study led by researchers with the Southern California Permanente Medical Group, Pasadena, found no association in COVID-19 positivity rates among healthcare workers (HCWs) wearing respirator masks vs medical masks when performing nonaerosolizing, routine patient care.

Of 1,414 HCWs involved in the study:

• 595 (42.1%) had exposures to COVID-19
• 961 (68%) developed symptoms
• 438 (31%) worked in high-risk areas
• 396 (28%) had underlying health conditions
• 302 (21.4%) wore respirator masks
• 724 (51.2%) wore medical masks
• 388 (27.4%) wore no masks.

Unadjusted analysis found no difference in HCW positivity between those wearing respirator masks vs medical masks. However, a statistically significant lower positivity was found when HCW wore respirator masks vs no masks and when they wore medical masks vs no masks. After adjusting for confounders, the researchers found a similar association between mask use and HCW positivity.

More than 95% of HCWs acquired COVID-19 outside of a known patient-related exposure event, possibly because of improper donning and doffing of masks during social interactions with other HCWs in the workplace or in the community, the researchers note.