The evidence behind a federal plan to rollout COVID-19 vaccine booster shots to Americans beginning the week of Sept. 20, pending FDA review, has left some experts divided. 

The shots would be offered to individuals whose second dose of a COVID-19 vaccine was eight months ago. During a White House briefing, Centers for Disease Control and Prevention (CDC) Director Dr. Rochelle Walensky cited several studies indicating waning protection against infection over time. One study out of New York from May to July saw vaccine efficacy against new COVID-19 diagnoses slide from 92% to 80%, and a preprint from the Mayo Clinic saw Pfizer’s vaccine efficacy against infection plummet from 76% to 42% in the face of the delta variant, with Moderna’s efficacy decreasing from 86% to 76%.

However, the vaccines remained effective against hospitalization.

"[I] need more data to convince me to do this as a wholesale public health policy," Dr. Gregory Poland, professor of medicine, infectious diseases and molecular pharmacology at the Mayo Clinic, told Fox News.


Several experts told Fox News that federal health officials’ proposed plan to rollout booster shots to most Americans come September is premature, whereas clear evidence supports a third dose among vulnerable patients with weakened immune systems (i.e. immunocompromised individuals). 

"In my opinion, a recommendation for all individuals to have a booster dose starting 8 months after an individual’s 2nd mRNA dose is too soon," Dr. Ravina Kullar, infectious diseases specialist, epidemiologist and adjunct faculty at David Geffen School of Medicine at UCLA, told Fox News.

Dr. Marc Siegel, Fox News medical contributor, agreed, adding that booster shots should go to immunocompromised populations and those at highest risk of exposure who were first to receive the vaccines. The move to quickly recommend booster doses across the larger population risks undermining confidence in the vaccine, he said.

Several experts pointed to evidence out of Israel, which is weeks into its COVID-19 booster rollout, and just extended third shots to people aged 40 and up. Siegel, and Dr. Aaron Glatt, chairman of the department of medicine and chief of infectious diseases at Mount Sinai South Nassau, said the U.S. can look to Israel to gain insight in navigating the issue of booster doses.

"I think there will most certainly be patients that absolutely will benefit from getting a third dose, besides the immunocompromised that definitely should get a third dose," Glatt said. "I think there will be some patients that probably have robust immunity and really don’t need a third dose at this point in time, maybe they’ll never need it, that we don’t really know."

"At this point in time, we just don’t have enough information to know who would best benefit from it," he continued. 

"I think that there is some evidence, we need more evidence and I think that we’re gathering more evidence," he said.

The debate over extending booster shots to the larger U.S. population despite the World Health Organization’s call for wealthier countries to halt booster shots as the developing world grapples under vaccine scarcity also stirred conflicting responses from experts. 


"…This is a global problem, providing an additional dose of the vaccine to most American people also depletes the limited global supply of vaccines with most developing countries still facing the reality of having no vaccines available," Kullar told Fox News.

However, others disagree, including Siegel who suggested the global effort requires bolstered manufacturing capabilities, instead of the U.S. donating extra doses.

"It’s like a drop in the ocean," he said. 

President Biden on Thursday shared a similar statement, telling ABC News’ George Stephanopoulos in part: "We're providing more to the rest of the world than all the rest of the world combined," a transcript reads in part.