The CDC (Centers for Disease Control and Prevention) said on Thursday that masks and social isolation are no longer required for people who have been fully vaccinated against Covid-19. The agency stated that the decision was motivated by scientific evidence that the vaccines play a significant role in reducing both infections and virus transmission.
CDC Director Dr. Rochelle Walensky said there are “numerous reviews in the literature” demonstrating the safety and real-world efficacy of Covid-19 vaccines in announcing the agency’s revised guidelines.
Comprehensive Coverage of the COVID-19 Outbreak
Walensky cited three recent studies that showed the vaccines’ effects on symptomatic and asymptomatic infections, as well as one report published only last week on the efficacy of Covid-19 vaccines against two variants that are reported to be circulating in the US.
The findings add to an increasing body of evidence that the vaccines are successful at preventing Covid-19-related serious illness and death, as well as helping to prevent the virus from spreading to others.
“The trends are all going down because vaccines are making a big difference,” said Dr. Isaac Weisfuse, a medical epidemiologist at Cornell University and former New York City deputy health commissioner. “The fewer people you have who are susceptible, the more likely the trends will keep going down.”
The number of newly recorded Covid-19 incidents, hospitalizations, and deaths in the U.S. are all declining. According to Walensky, the most recent seven-day average for new cases fell by around 23% from the previous week. According to the CDC, the seven-day average for daily deaths fell to 587 a day.
“Today, Covid-19 deaths are at the lowest point since April 2020,” Andy Slavitt, White House Covid-19 adviser, said in a news briefing on Thursday.
Dr. Monica Gandhi, an infectious disease physician and professor of medicine at the University of California, San Francisco, said “these numbers help to reinforce that the vaccines are working — and working well.”
“It’s like we reached a tipping point in terms of the weight of the evidence showing that these are profoundly effective vaccines, beyond our wildest dreams, and they’re really good at blocking transmission,” Gandhi said.
According to Dr. David Dowdy, an associate professor of infectious disease epidemiology at the Johns Hopkins Bloomberg School of Public Health, the shift in guidelines was long overdue.
“I think part of the problem before this was that there was something of a mixed message: The vaccines are very effective, but you still have to wear a mask,” Dowdy said. “This is now a strong statement that we know these vaccines work, and for those who are fully vaccinated, it’s appropriate to take some steps toward living life a bit more normally.”
The Pfizer-BioNTech vaccine was shown to be 97 percent effective at protecting against symptomatic infection and 86 percent effective at protecting against asymptomatic infection in one of the studies cited by the CDC. The findings were based on a survey of more than 6,700 vaccinated health care workers in Israel, and were published in the Journal of the American Medical Association on May 6.
The Pfizer-BioNTech vaccine was found to be 97% effective against symptomatic infection and 86% effective against asymptomatic infection in one of the studies cited by the CDC. The findings were based on a survey of over 6,700 vaccinated health care workers in Israel, which was published in the Journal of the American Medical Association on May 6.
Walensky also cited two recent reports from the United States that appeared in the CDC’s Morbidity and Mortality Weekly Report. Covid-19 vaccines were found to be 90 percent successful in avoiding both symptomatic and asymptomatic infection in nearly 4,000 health care and front-line staff in one study.
In a second study, adults 65 and older who had been completely vaccinated showed that the Pfizer and Moderna vaccines were 94 percent successful in preventing Covid-19-related hospitalizations.
Gandhi said that the CDC research on adults aged 65 and up was especially significant because there were early questions about how well vaccines might work in older populations.
“The cumulative weight of all these studies show that taking masks off a vaccinated person is completely fine,” she said.
Although it is possible for someone who has been completely vaccinated to become infected, these infections are extremely uncommon. Just 9,245 people out of more than 117 million people in the U.S. tested positive for Covid-19 after being completely vaccinated. The CDC also stated that illnesses caused by breakthrough infections are usually mild.
Walensky also mentioned the findings of a study published in The New England Journal of Medicine on May 5 that looked at the efficacy of Pfizer’s coronavirus vaccine against two different coronavirus variants.
The vaccine was 89.5 percent successful at preventing infection from the so-called B.1.1.7 variant, a more infectious strain of the virus that was first identified in the U.K., according to the study, which was focused on the findings of a mass vaccination campaign in Qatar. The Pfizer vaccine also proved to be 75 percent effective against the B.1.351 strain, which was first discovered in South Africa.
These findings are important because vaccines against the B.1.351 variant have been deemed ineffective, and the B.1.1.7 variant has taken hold in the United States, becoming the dominant strain in early April.
It’s likely that new strains of the virus will appear, forcing the CDC to change its advice, but Dowdy believes now is the best time to relax restrictions for those who have been completely vaccinated.
“If and when those variants emerge, we will react accordingly,” he said. “But the important message right now in the U.S. is that things are trending in the right direction, to a place where we’re able to recommend to over one-third of Americans that they can now take off their masks.”
According to Weisfuse, the updated guidance is a significant milestone for the country and a breakthrough in the course of the pandemic.