As a sense of pre-pandemic normality returns and the new Delta variant emerges, should vaccinated people wear masks indoors?
Dr. Ashish Jha, professor and dean of Brown’s School of Public Health, weighed this question Wednesday in an op-ed from the Boston Globe. His answer – it depends.
“It’s confusing,” Jha said. “So who’s right, and how should Americans navigate this?”
In the op-ed and in a tweet, Jha referred to how the World Health Organization (WHO) and the Los Angeles Health Department say everyone should wear masks indoors, while the Center for Disease Control and Prevention (CDC) says those vaccinated must not need.
“Well, it turns out it’s nuanced,” Jha wrote in the tweet. “It depends a lot on where you live … and your risk tolerance.”
In Massachusetts, the mandate to mask indoor spaces – excluding public transportation, health facilities and any vulnerable population settings – was lifted on May 29. The Department of Health still requires unvaccinated people to continue wearing their masks.
Jha explained the two sides by discussing the logic behind both and how they play out in different populations.
“If you are fully vaccinated and encounter the Delta variant, you are approximately 90 percent less likely to be infected than if you had not been vaccinated,” Jha wrote. “And if you get infected, you’re very unlikely to get very sick.”
Despite the effectiveness of the vaccine, Jha said the risk is much higher in areas where many people are still unvaccinated.
“If a vaccinated person encounters the virus repeatedly or in high enough concentrations, the chances of a breakthrough infection increase,” Jha wrote.
Massachusetts has more than double the fully vaccinated population of the total persons eligible for Mississippi. Jha compared the vaccine to the star goalkeeper from a hockey team – Gerry Cheevers in his example – who blocks the virus instead of the puck.
“In Massachusetts, there is not much virus around putting a shot at the target at all, and therefore little reason to wear a mask indoors,” Jha wrote. “In Mississippi, there are simply many more shots on goal, and even a great goalkeeper will occasionally let in a shot.”
Jha also said since there is no system to control who is vaccinated, many non-vaccinated people do not wear masks indoors despite being advised to do so.
“Indoor masking cannot be enforced on unvaccinated people only without [a] vaccine verification system, ”tweeted Jha.
As for himself, Jha says while living in New England – a heavily vaccinated area – he wears masks at intervals depending on the amount of crowd.
“If I was in SW Missouri and many other places with low wax, high cases, I would wear a mask indoors reliably,” Jha tweeted. “Your preferences may vary.”
Jha ultimately concludes that there is no correct answer because so much varies from state to society.
“As we move through this pandemic, we are now entering a phase where guidance will – and should – be local and will change as realities on earth change,” Jha wrote.
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