Federal health officials are once again recommending that Americans in about 60% of U.S. counties with “substantial or high” rates of COVID-19 begin wearing masks in public indoor spaces, citing the more infectious delta variant.
The Centers for Disease Control and Prevention said Tuesday afternoon that it is also recommending that all students in K-12 schools wear masks, regardless of vaccination status. This includes teachers, staff, and school visitors. (Children who are at least 12 years are eligible for Pfizer Inc.
The shift in tone comes at a time when the pandemic in the U.S. has worsened in recent weeks and the national vaccination rate has stalled at about 49%.
“This moment, and most importantly, the associated illness, suffering, and death could have been avoided with higher vaccination coverage in this country,” Dr. Rochelle Walensky, director of the CDC, told reporters on Tuesday. “The vast majority of transmission occurring is occurring through unvaccinated individuals.”
The seven-day average in the U.S. is 56,816 new cases per day and 281 deaths per day, as of July 26, according to the CDC. A month ago, the seven-day average was 12,471 cases per day and 262 deaths per day.
The CDC organizes community transmission into four categories: low (blue), moderate (yellow), substantial (orange), and high (red). Much of the South is currently considered to have high rates of transmission, as are large swaths of Western states such as Nevada, Utah, Wyoming, and Arizona.
More than 63% of U.S. counties are categorized as having “high” or “substantial” rates of transmission.
Tuesday’s announcement is a splash of cold water after months of steps forward.
The CDC in mid-May told Americans who had been vaccinated that they no longer need to wear masks or social distance in most settings. Two months later, the public-health agency rolled back rules in K-12 schools, saying vaccinated teachers and students do not need to wear masks.
With vaccination rates rising for much of the spring, capacity limits in bars, restaurants, and gyms were lifted. Event venues reopened. People began traveling again. Walensky herself tweeted that she finally hugged her mother in May.
“At 18 months through this pandemic, not only are people tired, they’re frustrated,” Walensky said. “We have a lot of continued sickness and death in this country. Our health systems are, in some places, being overrun for what is preventable. And I know, in the context of all that, it is not a welcomed piece of news that masking is going to be a part of people’s lives who’ve already been vaccinated.”
The rapidly spreading delta variant, which is now the most dominant strain of the virus in the U.S., has put the unvaccinated in its crosshairs, and it also puts the vaccinated at risk, albeit a much lower one.
Infections among the vaccinated, which are called breakthrough infections, are considered rare, to be expected, and significantly more likely to lead to mild or moderate forms of COVID-19. But the CDC shared new data that indicates breakthrough infections are more common than previously thought, and vaccinated people who test positive for the virus carry a similar viral load to those who are not vaccinated and test positive.
“If you have a vaccinated individual who is in a place with substantial or high transmission, they’re contacting a lot of people,” Walensky said. “One in 20, one in 10, of those contacts could potentially lead to a breakthrough infection if you have effectiveness of 90% to 95%.”
Pfizer and Moderna Inc.’s
COVID-19 vaccines were both about 95% efficacious in clinical trials and thought to be around 90% effective in the real world. The CDC last shared data in May about breakthrough infections, saying that there were less than 10,000 breakthrough cases out of the 95 million people who were fully immunized at that time.
However, now it seems that the amount of SARS-CoV-2 in vaccinated individuals is “pretty similar” to that in unvaccinated people, according to Walensky. The CDC is studying the transmission risks from someone who is vaccinated to someone who has not been immunized.
“We’re seeing now that it’s actually possible if you’re a rare breakthrough infection that you can transmit further, which is what the reason for the change with regard to schools,” Walensky said.