By Brianna Abbott 

Behind the decision by federal health officials to effectively end face- mask and distancing recommendations for the fully vaccinated, they said, was a mix of recent research, increasing vaccinations and declining case counts.

The guidelines now largely follow the growing body of scientific evidence on the effectiveness of the vaccines against Covid-19, especially given the current state of the pandemic in the U.S., according to public-health specialists.

Parsing the new recommendations and putting them into practice now shifts to states, communities and businesses. It will likely be especially difficult in public settings like stores or workplaces, health researchers say, since there isn't an easy way to determine who is fully vaccinated.

"There are states that I believe will continue to require masks in public spaces, simply because we cannot tell who is vaccinated or who is not," said Jennifer Nuzzo, an epidemiologist and senior scholar at the Johns Hopkins Center for Health Security.

The Centers for Disease Control and Prevention considers someone fully vaccinated two weeks after their second dose of the Pfizer Inc. and BioNTech SE or Moderna Inc. vaccines or two weeks following the single dose of the Johnson & Johnson vaccine.

Throughout the pandemic, the CDC has faced sniping from lawmakers, researchers and other health authorities on its pandemic response, including criticism that the federal agency bowed to political pressure and wasn't giving guidance specific enough for communities, schools and businesses to implement.

In the first several months after vaccines began rolling out, public-health authorities stood by recommendations for inoculated people to wear a face mask and stay physically distant, saying there wasn't enough data on whether the shots prevented infection and transmission. Another reason, the CDC said, was high case counts.

The CDC updated its masking guidance for fully inoculated people on April 27, saying that people who are fully vaccinated can drop their masks while alone outside or in small groups.

The change drew criticism from some people specializing in public health and members of the general public, who said the CDC was late to adapt to research emerging on the efficacy of vaccines and the spread of the virus.

The critics said the CDC was being too cautious with its previous guidance, particularly when it came to masking outdoors.

The CDC has said it needed to take the time to review the full body of evidence, which led to its latest recommendations.

CDC director Rochelle Walensky said on Thursday the fully vaccinated no longer needed to wear a mask indoors or outdoors, with some exceptions including at hospitals, airports and nursing homes.

Dr. Walensky pointed to data on the efficacy of vaccines, including against variants, case counts that have dropped to less than 37,000 a day in the U.S. and the launch of adolescent vaccinations.

Nearly 36% of the U.S. population is fully vaccinated, according to the CDC, and more than 46% of the country has received at least one dose. Among people 18 years and older, more than 46% are fully vaccinated.

Another factor informing the CDC decision, Dr. Walensky said, was recent research on transmission risk for those who are fully vaccinated and data on the vaccines' real-world effectiveness.

Authorized vaccines are effective at preventing people from getting infected and spreading the virus to others, in addition to preventing severe disease and death, according to the latest studies.

A number of studies, including one published last week, found that available vaccines are effective against circulating variants such as the B.1.1.7 variant, which is now the dominant variant in the U.S.

A recent study from researchers in Israel, which Dr. Walensky referenced on Thursday, estimated the Pfizer-BioNtech vaccine was 97% effective at preventing symptomatic infection and 86% effective at preventing asymptomatic infection among healthcare workers.

A study released Friday by the CDC, looking at healthcare workers in 25 states, reported that the mRNA vaccines from Pfizer and BioNTech and Moderna were 94% effective at reducing the chances of getting sick.

"This report provided the most compelling information to date that Covid-19 vaccines were performing as expected in the real world," Dr. Walensky said. "This study, added to the many studies that preceded it, was pivotal to CDC changing its recommendations for those who are fully vaccinated."

The CDC's justification for some parts of the guidance, such as requiring vaccinated people to wear masks on public transportation but not in other crowded indoor settings, aren't entirely clear and might have more to do with logistics, said Isaac Weisfuse, a medical epidemiologist at Cornell University.

"There are all these situational issues that are based on these recommendations that are not so clear," Dr. Weisfuse said. "I think it's good about following the science, but there are a lot of details that are missing."

Write to Brianna Abbott at brianna.abbott@wsj.com

 

(END) Dow Jones Newswires

May 14, 2021 16:40 ET (20:40 GMT)

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