Why the change?

Local health officials are encouraging mask-wearing indoors for all “ultimately for the protection of unvaccinated individuals” from the delta variant.

Health officials across seven Bay Area counties on Friday recommended that everyone — even vaccinated people — wear masks during indoor activities like shopping.

That goes beyond the guidance given by the state and federal governments, which say that vaccinated people need not wear masks in most indoor settings.

So why are Bay Area health officials changing their advice?

The answer, put simply, is that masking is an easy way to

keep people — especially those who are unvaccinated — safer as the highly contagious delta variant spreads.

Even though the Bay Area has one of the highest overall vaccination rates in the country, hundreds of thousands of residents have not been vaccinated, including children who are 11 or younger because they’re not yet eligible.

The recommendation “is really ultimately for the protection of unvaccinated indi

viduals, especially in the setting of the more contagious delta variant,” said Dr. Sarah Rudman, assistant health officer for Santa Clara County.

And it’s impossible to tell in a store who’s vaccinated or not, so having a universal recommendation for everyone will ensure compliance.

San Francisco Health Officer Dr. Susan Philip said that even in a place like San Francisco with high vaccination rates, there are plenty of people who remain vulnerable to the disease.

“I’m not worried about the vaccines not working against delta, but I also know we want to be able to uniformly know that everyone indoors is equally protected right now,” Philip said. “We can’t tell who is vaccinated and who is not, so to increase safety across the city — go ahead and put masks back on.”

What may seem like a small

rise in cases is likely to develop into a steady trend of unvaccinated people getting infected because “more cases breeds more cases,” Marin County Public Health Officer Dr. Matt Willis said.

The vaccines are proving to be highly effective at preventing serious illness and death, but vaccinated people who get infected could potentially pass the virus to others, Willis said.

About 1 in 4 new coronavirus cases in Marin County are occurring among vaccinated people, according to Willis. Most of these people are asymptomatic or have mild illness, but it suggests wearing masks while indoors can help protect those who are most vulnerable.

“We don’t want the message to be the vaccine isn’t effective with the delta variant,” Willis said. “People aren’t getting nearly as sick. But unvaccinated people remain vulnerable, our kids and other people are just as at risk of getting ill as they ever were.”

Art Reingold, professor of epidemiology with the UC Berkeley School of Public Health, called the mask recommendation “perfectly reasonable.” He said the most effective defense against COVID19 is a vaccine, but other prevention methods like masks and keeping distance from others in public places are also crucial tools to use at a time when not everyone has chosen to get inoculated.

Reingold said he continued wearing a mask in grocery stores and other indoor places even though it wasn’t required once he was fully vaccinated because it was a simple and effective practice. He said the next six months could present challenges in the effort to stamp out COVID19 because of lagging vaccination rates and seasonal upticks in illness.

“You have an added measure of protection when you’re in an indoor space with strangers and you don’t know whether they’re vaccinated or not,” Reingold said. “Clearly it also contributes to the community spirit, if you will. We’re all in this together. Masks are a good thing.”