When Can We Stop Wearing Masks?
By: Robert Roy Britt
Tags: Vaccines, Pandemic, Covid 19, Coronavirus, Masks

Photo by Anton on Unsplash

When Can We Stop Wearing Masks?

Vaccines are promising, but don’t toss that face covering just yet

From a scientific perspective, there’s no longer any question that face masks help prevent the spread of Covid-19, protecting both the wearer and others. So with optimism rising over vaccines that appear to be highly effective, one big question now is how long we’ll all be bound to cover our faces, especially since new cases and deaths continue to soar.

The answer: Longer than you might have hoped.

Key factors include how quickly a sizable majority of the population gets vaccinated, plus a big wild card: whether the vaccines actually prevent infection, either mostly or entirely, or merely prevent and curb symptoms while leaving an infected person still potentially infectious.

In the meantime, infectious-disease experts stress the ongoing importance of masks in a layered approach to prevention that still includes avoiding crowds and poorly ventilated spaces, washing hands frequently, then getting the vaccine when your turn comes.

“Even after being immunized it will be important for people to continue to wear masks until we hear that the pandemic is under control, many people have been immunized, and community levels of disease are at acceptably low levels,” says David Aronoff, MD, director of the Division of Infectious Diseases at the Vanderbilt University School of Medicine. “While vaccines will prevent symptomatic infection, we do not know whether vaccines will completely prevent infection in the first place, or prevent transmission of the SARS-CoV-2 virus.”

Vaccines are never perfect

For comparison, the annual flu shot — more important than ever this year — is typically around 50% effective. It fully protects some individuals, and if a vaccinated person does catch the flu, their symptoms are likely to be less severe and of shorter duration than a nonimmunized person, and during that time they could still transmit the disease to someone else, Aronoff explains.

“I am hopeful that SARS-CoV-2 vaccines prevent infection and eliminate contagiousness,” he tells me. “But we need to behave as if they reduce symptoms, prevent severe disease, shorten the duration of viral shedding, and reduce but not eliminate contagiousness.”

Multiple Covid-19 vaccines are getting high marks from scientists not involved in their creation, including Eleanor Murray, ScD, assistant professor of epidemiology at Boston University’s School of Public Health. But Murray echoes Aronoff on the notion that there’s more to learn before we know how high the high fives should go.

“The randomized trials showed us that the vaccines do a great job preventing illness, but haven’t reported on infection status,” Murray says in an email. “We will likely learn more about this over the next few months as more people get vaccinated, though, so hopefully we’ll have the answer soon. If the vaccine does prevent transmission, then we’ll need to wear masks until maybe about 70% of the people in our communities are vaccinated. If the vaccines don’t prevent transmission, we may need to wear masks longer than that.”

That 70% figure is a rough estimate of what it takes for herd immunity to significantly kick in, presumably slowing the spread of the virus because it begins to run out of people to infect.

Dr. Anthony Fauci, the nation’s top infectious-diseases expert, said on December 15 that an even lower level of immunization could start to slow the pandemic down by late spring or summer and potentially “turn this thing around” by the end of 2021.

“I would say 50% would have to get vaccinated before you start to see an impact,” Fauci told NPR. “But I would say 75 to 85% would have to get vaccinated if you want to have that blanket of herd immunity.”

Spring? Summer? Fall?

Fauci’s timeline depends on those vexing unknowns, however.

“There is a big if to this,” says Marc Lipsitch, PhD, a professor of epidemiology and director of the Center for Communicable Disease Dynamics at Harvard T.H. Chan School of Public Health. Herd immunity thresholds cited by Fauci depend not just on the number of shots taken, but on whether the Covid-19 vaccines prevent infection, infectiousness, and transmission as well as, say, measles and mumps vaccines, Lipsitch tweeted December 15, or if they mainly prevent symptoms and have only modest effects on transmission, as is the case with vaccines for some other diseases.

It’s also not yet clear how rapidly vaccines will be deployed to the entire population.

“I don’t think we should stop wearing masks indoors, especially in spaces that we do not know what the ventilation/filtration rates are and that are crowded until the general public starts to get vaccinated, and that will not be until close to next fall, I suspect,” says Shelly Miller, PhD, an environmental engineer at the University of Colorado, Boulder, who studies the indoor transmission of infectious diseases.

Until then, the importance of masking up is no less crucial — and far more so when in crowded indoor spaces and especially in poorly ventilated places, versus the comparatively lower risk outside with good airflow and proper physical distancing. Risk is also high if someone brings the virus home, and there are several ways to mitigate that challenge.

Since masks are here to stay for a while, here’s an in-depth guide to choosing the best face coverings and dealing with the many issues they present: