The U.S. Centers for Disease Control and Prevention on Friday backed a booster shot of the Pfizer and BioNTech COVID-19 vaccine for Americans aged 65 and older, adults with underlying medical conditions and adults in high-risk working and institutional settings.
The move comes after an advisory panel to the agency on Thursday did not recommend that people in high-risk jobs, such as teachers, and risky living conditions should get boosters. The panel had recommended boosters for elderly and some people with underlying medical conditions.
CDC Director Rochelle Walensky said her agency had to make recommendations based on complex, often imperfect data.
"In a pandemic, even with uncertainty, we must take actions that we anticipate will do the greatest good," she said in a statement.
"I believe we can best serve the nation's public health needs by providing booster doses for the elderly, those in long-term care facilities, people with underlying medical conditions, and for adults at high risk of disease from occupational and institutional exposures to COVID-19. This aligns with the FDA's booster authorization and makes these groups eligible for a booster shot," she said.
The CDC recommendation follows U.S. Food and Drug Administration authorization and clears the way for a booster rollout to begin as soon as this week for millions of people who had their second dose of the Pfizer shot at least six months ago.
Bernd Salzberger, head of infectiology at Regensburg university hospital in Germany, said that given uncertainty over the durability of protection experts could easily come to different conclusions over who should be eligible for boosters and when.
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"The United States are currently undergoing a more severe wave of infections than here because there are many more unvaccinated in several states, mainly in the South. That could be a reason for someone to say we must protect health care workers in particular," said Salzberger.
The CDC said people 65 years and older should get a booster and also recommended the shots for all adults over 50 with underlying conditions.
It said that, based on individual benefits and risks, 18- to 49-year-olds with underlying medical conditions may get a booster, and also people 18-64 at increased risk of exposure and transmission due to occupational or institutional settings.
The recommendations cover only people who received their second Pfizer/BioNTech shot at least six months earlier. The CDC said that group is currently about 26 million people, including 13 million age 65 or older.
The CDC's Advisory Committee on Immunization Practices on Thursday gave the thumbs down to additional doses for groups including healthcare workers, teachers and residents of homeless shelters and prisons.
Panel member Lynn Bahta, who works with the Minnesota Department of Health, voted against that measure. She said the data does not support boosters in that group yet. "The science shows that we have a really effective vaccine," she said.
The committee had said it could revisit the guidance later.
Last month, U.S. President Joe Biden and eight top health officials said they hoped to start a broad booster shot program this week, saying data showed immunity wanes over time.
Vaccine expert Dr. Paul Offit said he believed the CDC advisers were worried that recommending boosters based on employment would allow overly broad use.
"That was a hole that you could drive a truck through, that essentially what we were doing was basically what the (Biden) administration initially asked - to just have a vaccine for the general population, because obviously the pharmacists aren't going to figure out whether you're working in a grocery store or hospital," he said.
More than 180 million people in the United States are fully vaccinated, or about 64 percent of the eligible population.
Pfizer – and some top U.S. health officials like Dr. Anthony Fauci – have argued that the extra round of shots are needed to address waning immunity. Fauci and others have also said they could help contain surging hospitalizations and deaths caused by the highly transmissible Delta variant of the coronavirus by cutting breakthrough infections of fully vaccinated people.
Some countries, including Israel and Britain, have already begun COVID booster campaigns. The United States authorized extra shots for people with compromised immune systems last month and around 2.3 million people have already received a third shot, according to the CDC.