U.S., international scientists say COVID-19 vaccines do not currently 'show a need for boosting'

The current evidence on COVID-19 vaccines does not appear to support a need for booster shots in the general public right now, according to an international group of vaccine scientists, including some from the U.S. Food and Drug Administration and the World Health Organization.

"Current evidence does not, therefore, appear to show a need for boosting in the general population, in which efficacy against severe disease remains high," the scientists write in a new opinion piece, published Monday in the medical journal The Lancet.

The authors of the paper include two senior FDA vaccine leaders, Dr. Philip Krause and Marion Gruber, who will be stepping down in October and November, the FDA announced late last month. No further details were released about their retirements, although they sparked questions about whether the departures would affect the agency's work.

• Newsletter sign-up: Get The COVID-19 Brief sent to your inbox

The FDA and other public health agencies around the world continue to examine evidence on COVID-19 vaccine efficacy and the role booster doses of vaccine might play in improving immunity against the disease.

For the new paper in The Lancet, the scientists note that they reviewed randomized trials and observational studies on COVID-19 vaccines and consistently find that "vaccine efficacy is substantially greater against severe disease than against any infection; in addition, vaccination appears to be substantially protective against severe disease from all the main viral variants. Although the efficacy of most vaccines against symptomatic disease is somewhat less for the delta variant than for the alpha variant, there is still high vaccine efficacy against both symptomatic and severe disease due to the delta variant."

The scientists note that there is an opportunity right now to study variant-based boosters before there could be a widespread need for them. But they also argue in their paper that the current COVID-19 vaccine supply could "save more lives" if used in people who are not yet vaccinated than if used as boosters. In early August, the World Health Organization called for a moratorium on booster shots until at least the end of September.

"To date, none of these studies has provided credible evidence of substantially declining protection against severe disease, even when there appear to be declines over time in vaccine efficacy against symptomatic disease," the scientists write in their paper.

"The limited supply of these vaccines will save the most lives if made available to people who are at appreciable risk of serious disease and have not yet received any vaccine. Even if some gain can ultimately be obtained from boosting, it will not outweigh the benefits of providing initial protection to the unvaccinated," the scientists write. "If vaccines are deployed where they would do the most good, they could hasten the end of the pandemic by inhibiting further evolution of variants."

The paper published just shy of a month after U.S. federal health officials announced plans for booster doses of COVID-19 vaccine to be offered this fall, starting September 20, subject to authorization from the FDA and sign off from the U.S. Centers for Disease Control and Prevention.

The FDA's Vaccines and Related Biological Products Advisory Committee is meeting this Friday to discuss vaccine makers Pfizer and BioNTech's application to administer their COVID-19 vaccine as a third dose, or "booster" shot, to people ages 16 and older.

"The message that boosting might soon be needed, if not justified by robust data and analysis, could adversely affect confidence in vaccines and undermine messaging about the value of primary vaccination. Public health authorities should also carefully consider the consequences for primary vaccination campaigns of endorsing boosters only for selected vaccines," the scientists write in their new paper. "Booster programmes that affect some but not all vaccinees may be difficult to implement—so it will be important to base recommendations on complete data about all vaccines available in a country, to consider the logistics of vaccination, and to develop clear public health messaging before boosting is widely recommended."

CNN has reached out to the FDA for comment on the Lancet review.

WHO PUSH TO WAIT ON BOOSTERS

Last week, WHO Director-General Tedros Adhanom Ghebreyesus reiterated his call for wealthy nations to refrain from boosting their COVID-19 vaccinations until shots are available to more of the world. He urged countries to wait until at least the end of the year -- a longer timeline than WHO's initial call to wait till the end of September.

"Low and lower-middle income countries are not the second or third priority. Their health workers, older people, and other at risk groups have the same right to be protected," Tedros said.

"I will not stay silent when the companies and countries that control the global supply of vaccines think the world's poor should be satisfied with leftovers."

White House press secretary Jen Psaki then reiterated the Biden administration's view that the U.S. can offer COVID-19 booster shots to Americans this fall while at the same time working to provide vaccines to people around the world who have not yet received a shot.

"Our view is that this is a false choice," Psaki told reporters at a White House briefing. "And the United States has donated and shared about 140 million doses with over 90 countries -- more than all other countries combined."