Why do I need to wear a mask if I’ve been immunized?

1. We know that the COVID vaccines from Pfizer and Moderna are quite good at preventing serious illness and milder symptomatic disease. But we don’t yet know (studies are ongoing and we will have more information soon) if the vaccines prevent asymptomatic infection.  That particular endpoint wasn’t studied in the vaccine trials.
2. Respiratory infections like COVID-19 gain entry to our bodies via the nose, and rapidly multiply there. If a vaccinated person were in contact with an infected person, virus particles could infect the nose mucosa of the vaccinated person and without having any symptoms, they could become silent spreaders of infection to others. Especially if they stop wearing masks and social distancing.
3. The vaccine is injected into an arm muscle (and not sprayed as a mist into the nose), and broadly stimulates many branches of the immune system: B and T cells, antibody production, memory immune cells and some immune cells migrate to the lining of the nose and mouth where they provide important local defense. We don’t yet know how well vaccine-induced immunity will boost the mucosal immunity in the lining of the nose and mouth, and how effective it will be in shutting down viral replication to avoid infecting others. Until then, wearing a mask will continue to protect those around us, help to avoid surges, and slowly help get life back to normal.

Sky Pittson, MD,  January 20, 2020