Could Masks Help Build Immunity?

It’s all about the “viral inoculum theory,” according to infectious-disease experts.

Woman wearing a mask to protect her from Covid-19

In the early days of the coronavirus pandemic, public-health authorities advised people to wear masks as a selfless act to prevent spreading germs and protect other people. Now, as knowledge of the virus and case histories accrue, experts cite growing evidence suggesting that masks also protect the mask wearer.

They may also lessen COVID-19 symptom severity or even help avert infection entirely.

Rather than going without a mask and getting floored with a heavy viral load all at once, people wearing even simple cloth masks versus nonsurgical N95 respirators may reduce their exposure to coronavirus pathogens over time. This could allow our systems to build up immunity, according to the thesis of a new paper published in the Journal of General Internal Medicine.

“Masks filter out the majority of viral particles for the person wearing them. So, masks protect you from getting sick even if you do get infected because you take less of the virus into your system and are more likely to have mild infection,” explains lead author and infectious-disease expert Monica Gandhi, MD, MPH, a professor of medicine at the University of California, San Francisco, and director of the school’s Center for AIDS Research.

The authors cite several animal and human studies that reinforce the “viral inoculum theory,” as well as pointing to the overall low sickness and death rate among masked healthcare workers. They also note numerous instances around the world where mandated masking has resulted in higher levels of asymptomatic infection among the population and lower death rates.

All of this could lead to greater community-level immunity at a quicker pace, Gandhi states.

“If we get more population-level immunity from mild disease and asymptomatic infection, then we will slow down this virus on its own without the terrible consequences of severe illness and death,” she says. “Masking could minimize the severe illness from this infection and get us to enough herd immunity to achieve intermediate-level control while we await an effective vaccine.”

is Experience Life deputy editor.

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