In another vote, advisers recommended adding language on the shot’s risks to the vaccine’s information sheet, which is already required by law.

The committee’s focus on Covid-19 vaccines reflects Kennedy’s long-held suspicion of them. Since taking office in February, Kennedy has canceled a half-billion dollars in mRNA vaccine research and separately ended a major contract with Moderna, one of the Covid vaccine manufactures, for work on a pandemic bird flu vaccine.

During Friday’s meeting, CDC scientists presented extensive data on the safety and efficacy of the Covid vaccines. They also explained in detail how the agency tracks Covid hospitalizations and said the agency has a “rigorous and standardized process” to determine whether hospitalizations are classified as being due to Covid-19.

During the discussion portion of the meeting, committee members made several unfounded claims. Robert Malone, a former mRNA researcher who has spread vaccine misinformation, questioned whether there is actually evidence of disease protection from the Covid shots. “Are there any well-defined, characterized correlates of protection for Covid, yes or no?” he demanded.

Cody Meissner, a pediatrician at Dartmouth College, responded that there is “a reasonable measurement of neutralizing or binding antibodies that correlate with protection against symptomatic infection in the first few months” after vaccination.

At one point, Hillary Blackburn, a pharmacist on the committee, questioned whether the Covid vaccine could be connected to her mother’s lung cancer diagnosis, which occurred two years after receiving a Covid vaccine. She said she is aware of four other individuals in her small hometown diagnosed with the same kind of cancer. “Is it related to the vaccine?” she asked.

In a tense exchange about potential birth defects associated with the Covid vaccines, some ACIP members pressed manufacturer Pfizer about eight birth defects that occurred in a group of pregnant women who received the company’s vaccine and two birth defects that occurred in an unvaccinated group. Alejandra Gurtman, who heads vaccine clinical research and development at Pfizer, replied that those rates are comparable to rates of congenital abnormalities seen in the general population.

Carol Hayes, a liaison with the American College of Nurse-Midwives who was present during the meeting, clarified that most birth defects arise during the first trimester of pregnancy, and in the cited study, mothers received the vaccine at 12 to 24 weeks of pregnancy.

At Friday’s meeting, the committee also reversed a decision it made just a day before. On Thursday, advisers voted to no longer recommend the combined measles, mumps, rubella, and varicella (MMRV) vaccine to children under age 4. Yet puzzlingly, it voted to maintain coverage of that vaccine through the federal Vaccines for Children program, which provides free vaccines to low-income children and those without insurance. On Friday, they voted that the program should not, in fact, cover it.

On Friday, advisers also voted 11 to one in favor of tabling a decision on whether to delay the birth dose of the hepatitis B vaccine until one month of age. The committee had discussed that vaccine extensively on Thursday, though it’s unclear why the committee was asked to look into the potential change at all, as the hepatitis B vaccine has been given to newborns in the US since 1991.

Infants get the vaccine before leaving the hospital because the virus can be passed from an infected mother to the baby during birth. Hepatitis B is a serious liver infection that can lead to cirrhosis and cancer. The vaccine is highly effective at preventing infection in newborns.

Chari Cohen, president of the Hepatitis B Foundation, tells WIRED there is no scientific rationale for delaying the hepatitis B vaccine until one month after birth, and she worries about an increase in hepatitis B infections if the panel eventually recommends delaying the immunization.

“We will likely see more babies and young children who become infected,” Cohen says. “From a public health infrastructure perspective, we are concerned that this risk-based approach will miss preventing infection to babies born to infected moms.”

Up to 16 percent of HBV-positive pregnant women don’t get tested for hepatitis B, so screening doesn’t capture all infected mothers.

“We do not understand the motivation or rationale for this debate,” Cohen says.