WASHINGTON — Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, on Friday firmly blamed recent setbacks in preventing the spread of the delta variant of the coronavirus squarely on unvaccinated Americans who have defied federal guidance to continue wearing masks.
With the highly contagious delta variant of COVID-19 spreading nationwide, and new scientific data indicating that vaccinated people can spread the virus just as easily as those who have not been vaccinated, the CDC earlier this week reversed its guidance and said fully vaccinated Americans now should wear masks indoors.
“Our guidance in May said that fully vaccinated people could take off their masks safely, and that unvaccinated people should continue to wear them. Unfortunately, that’s not how it played out,” Walensky said in a phone interview with McClatchy. “Unvaccinated people took off their masks as well. And that’s what led us to where we are today.”
The CDC director said she expects a greater number of positive cases among vaccinated people — known as “breakthrough” cases — to surface in the coming weeks. As more people get vaccinated, the number of those cases will also go up, she said, especially with the amount of virus spreading throughout the country.
But the vaccines are working as intended according to the data, she said, noting that clinical trials for the vaccines produced by Pfizer and Moderna showed they were roughly 90% effective at preventing disease.
“People might come out and say, ‘Oh, my friend was vaccinated and got COVID,’” she said. “And what I would say is, if these vaccines are working at 90% protection against symptomatic disease, if you know 10 people who’ve been vaccinated, one of them may be a breakthrough case.”
The new CDC guidance recommends that vaccinated Americans resume wearing masks indoors if they are in a community with a significant or high rate of viral transmission.
Roughly 80% of the counties that have the most disease are places that have less than 40% of their residents vaccinated, she said.
But the contagiousness of the delta variant may still pose a threat to vaccinated individuals that is not yet fully known.
Walensky pointed to a recent study published in The New England Journal of Medicine outlining Israeli data that indicates a number of vaccinated people who experienced breakthrough cases have suffered from “long COVID,” or symptoms that have lasted for weeks or months.
“Some of their breakthrough infections have had disease for a long period of time,” Walensky said. “So I think data are going to start emerging in this area, but there is some concern based on that Israeli paper that that might be the case.”
The CDC is “carefully” examining data from clinical trials, vaccine manufacturers and international partners to see whether booster shots could be needed for vaccinated people — or help blunt the effects of the delta variant, she said.
“What I will say is, we are actively reviewing the data, and simultaneously actively working to ensure that the day the data signals that it is time to get a booster, we will be ready to deliver it,” she said.
The delta variant is among the most contagious infectious diseases scientists have seen in modern times and swept the country to become the most dominant strain of the coronavirus in the United States in just two months. “When I think of infectious infectious diseases, this delta variant is topping my list,” Walensky said.
The CDC director warned that the virus would evolve — potentially into even more contagious and deadlier forms — if it is able to continue mutating in unvaccinated hosts.
Walensky declined to predict how long Americans would have to wear masks going forward.
“This whole pandemic has been humbling,” she said. “The science evolves quickly – as the science evolves, my responsibility is to deliver that information to the American people so that they can protect themselves. So I would think it would be foolish of me to project where we’re going to be.”
“What I would say about how these variants evolve is that they evolve to survive,” she said. “One of the things I think we’re all worried about in the scientific community is if they evolve to survive to outsmart our vaccines. That is one possible path that they might use to evolve,” Walensky said.
“So could it become more transmissible? I suppose it could,” she added. “Could it evolve to evade our therapeutics? That is one possibility. Could it evolve to evade our vaccines? That’s certainly another possibility.”
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