Answers About Masks, the Delta Variant and Breakthrough Infections – The New York Times
The risk of being hospitalized or dying as a result of a breakthrough infection is minuscule (less than .003 percent), based on data collected from the C.D.C. As of June 21, more than 150 million people in the United States had been fully vaccinated against Covid-19. As of that date, the C.D.C. reported that 4,115 patients had Covid-19 vaccine breakthrough infections that resulted in hospitalization or death, including 3,907 who had been hospitalized and 750 who had died.
But because the risk of getting Covid-19 after vaccination isn’t zero, some health experts still advise that vaccinated people take reasonable precautions, like wearing a mask in crowded spaces.
People who live in areas with low vaccination rates may also want to consider wearing masks in public, where they are more likely to encounter an unvaccinated person than someone living in a highly vaccinated region.
In the United States, 63 percent of people 12 and older have received at least one dose and 54 percent are fully vaccinated. But in some cities like Seattle and San Francisco, more than 75 percent of those eligible are at least partially vaccinated. Many states in the Northeast, the West and Pacific Northwest have vaccinated more than 60 percent of the adult population. But the pace of vaccinations varies across the country. Several states in the South, including Mississippi, Louisiana, Alabama and Arkansas, have vaccinated fewer than 45 percent of adults. You can learn more from The Times’s vaccine tracker.
Dr. Paul Offit, a professor at the University of Pennsylvania and a member of the Food and Drug Administration’s vaccine advisory panel, is fully vaccinated but still wears a mask when he rides the bus in Philadelphia, because the rules require it, as well as when he’s in a crowded and enclosed space. He masks up when he shops at the grocery store, because he doesn’t know the vaccination status of the other shoppers. But he also dines in restaurants, as long as the tables are spaced at least four feet apart and the servers are wearing masks.
And even though the risk of breakthrough infections for fully vaccinated people is very low, Dr. Offit said the risk goes up when you’re in a community where most people aren’t vaccinated, because it creates more opportunities for you to encounter the virus. He cites a study in the Netherlands of the measles vaccine, which like the Covid vaccine offers high levels of protection, that found an unvaccinated person was safer in a highly vaccinated community than a vaccinated person in an area with low vaccination rates.
“If you’re in a highly vaccinated community you have sort of a moat around you,” he said.
Dr. Offit said the problem with the current guidance about mask wearing in the United States is that it requires trust.