Los Angeles County recently asked residents to start wearing masks in public again, due to the increased risk posed by the Delta variant of the virus that causes COVID-19. Days later, the CDC director said that vaccinated people are still “safe” and still don’t need to mask up in most public settings. Who’s right, and why the conflicting messages?
Vaccines are still highly effective against Delta
Vaccines may be slightly less effective against Delta compared to older forms of the virus, but they still work. Early data shows that the Pfizer vaccine is 88% effective against Delta (compared to 93% for Alpha, an earlier variant) if you have been fully vaccinated. Moderna announced that lab tests suggest its vaccine can neutralize all the variants, including Delta, and the Johnson & Johnson vaccine seems to be 60% effective.
It also seems likely that the vaccines are effective against severe disease, so that if you do get a breakthrough case, chances are it will be milder than if you hadn’t been vaccinated; Pfizer was 96% effective at preventing hospitalizations.
So if you’ve been vaccinated, you’re still mostly protected, but it’s reasonable to be a little extra cautious.
Delta is more contagious than other forms of the virus
Delta is a “variant of concern” for good reason: It’s more transmissible than other forms of the virus, it may cause more severe disease, and it’s less likely to be stopped by vaccines. The transmissibility is the most concerning aspect right now.
In the U.K., Delta makes up nearly all new infections; in the United States, it’s still just 20 percent. Delta may end up being the dominant strain here, too, because it’s more transmissible. The fact we’ve recently dropped mask requirements could be helping it spread, and pockets of low vaccination rates in some communities mean those places could be especially susceptible. Virologist Angela Rasmussen told Scientific American that hot weather in places like Arizona and Texas could result in more people sharing air as they congregate in indoor, air-conditioned spaces, leading to increased transmission in those areas.
Masking up more often could be a good idea
With what we know about Delta, vaccinated people are still not very likely to catch or transmit the virus—but the possibility is greater than with vanilla COVID.
Some settings, like hospitals and airports, require masks for everybody. (I traveled by air recently for the first time in forever; I appreciated the mask rule given that the planes were packed.) If you are vaccinated, you might want to wear a mask in crowded indoor areas, or places that otherwise feel high risk to you. I don’t wear a mask for most of my outings, but I do always have one in my pocket.
Here’s a helpful metaphor, from a New York Times piece on the conflicting messages:
“At this point, thinking about wearing a mask is a little like dressing for the weather,” said Linsey Marr, a professor of civil and environmental engineering at Virginia Tech and one of the world’s leading experts on viral transmission. “You need to consider the caseload and vaccination rates wherever you’re going, what activity you’ll be doing, and your own health.”
In parts of the world where Delta is the dominant variant, cases are high, and many people are unvaccinated, masks can help to get the situation under control. In other places, including parts of the United States, cases are low and vaccination rates are high, meaning that it’s relatively safe to go without a mask if you are vaccinated.
If you’re not vaccinated, it’s more important than ever to continue masking up to protect yourself. Children may not be required to wear masks in settings like schools anymore, but if cases are spreading in your area, it may be a good idea to wear them anyway. Masks can also help people with weakened immune systems, some of who may be more susceptible to the virus even if they have been vaccinated.