A US government advisory panel met Friday to decide whether to approve administering booster shots of Pfizer-BioNTech’s coronavirus vaccine, with Israeli health officials presenting figures indicating waning immunity against infection among all age groups around six months after vaccination.
The panel, made up of outside experts who advise the Food and Drug Administration, were scheduled to vote on one basic question: Does the evidence show that a Pfizer booster would be safe and effective for people 16 and older? In the event of a yes vote, the FDA is expected to quickly approve boosters for Pfizer’s shot.
Israeli experts presented the FDA with the findings of an Israeli study uploaded last month to online journal medRxiv ahead of peer review, comparing rates of infection and severe COVID during a several week period in July among people vaccinated at different times.
The study said people over 60 who received a second dose of the Pfizer vaccine in March were 1.6 times more protected against infection and 1.7 times more protected against severe morbidity than those who got a second shot in January. It added that similar figures were recorded in other age groups.
“These results indicate a strong effect of waning immunity in all age groups after six months. Quantifying the effect of waning immunity on vaccine effectiveness is critical for policymakers worldwide facing the dilemma of administering booster vaccinations,” the study says.
The figures were also included in a presentation Thursday by researchers from the Health Ministry, Gertner Institute, Hebrew University of Jerusalem, Technion University and Weizmann Institute of Science on vaccine effectiveness over time.
At Friday’s meeting, the FDA panelists heard full-throated arguments about the need for boosters from both Pfizer and health officials from Israel, which began offering boosters to its citizens in July.
Dr. Sharon Alroy-Preis, head of public services at the Health Ministry, told the FDA panel that the booster dose improves protection tenfold against infection in people 60 and older.
“It’s like a fresh vaccine,” bringing protection back to original levels and helping Israel “dampen severe cases in the fourth wave,” she said.
She also said it was too early to know whether booster shots will be needed every six months.
“I think it’s not very clear where this is going,” she said. “It may be that after the booster we’ll have a higher protection for a longer period of time.”
And representatives for Pfizer argued that it is important to shore up immunity before protection against severe disease starts to erode. A company study of 44,000 people showed effectiveness against symptomatic COVID-19 was 96% two months after the second dose, but had dropped to 84% by around six months.
Both Pfizer and the Israeli representatives faced pushback from panelists. Several expressed skepticism about the relevance of Israel’s experience to the US. Also complicating the committee’s decision: No one yet knows the antibody level below which infection is likely and boosters are needed.
“That would be a great way for us to monitor if we really needed booster shots,” said Dr. James Hildreth, president of Meharry Medical College.
FDA vaccine reviewer Dr. Philip Krause raised a host of questions about the reliability of one of the key studies Pfizer said showed that immunity is waning.
Another concern was whether third doses would exacerbate serious side effects.
Dr. Cody Meissner of Tufts Medical Center said he is worried about extra doses for younger age groups given the risk of heart inflammation that has been seen in mostly younger men after a second dose. While the condition is very rare, he said, it is not clear if that risk would increase with another dose.
Pfizer pointed to Israeli data from nearly 3 million boosters to suggest side effect rates would be similar to that seen after second doses.
On Wednesday, a study conducted in Israel was published that shows individuals given a third vaccine dose are nearly 20 times more protected against serious illness and more than 10 times more protected against infection, compared with those who received their second dose at least five months previously.
If the FDA panel gives the go-ahead for an extra dose of the Pfizer vaccine, the more thorny question of who should get the shots and when will be debated next week by advisers to the Centers for Disease Control and Prevention. The CDC generally adopts the group’s recommendations, which set policy for US vaccination campaigns.
Some group members have made clear they favor giving third doses to older people, nursing home residents and front-line health care workers, rather than all adults.
Separate FDA and CDC decisions will be needed for people who received the Moderna or J&J shots can get boosters.
Friday’s meeting came as the Delta variant continues to drive US cases and deaths back to levels not seen since last winter. That has given urgency to efforts by top health officials to shore up Americans’ protection against the virus.
Dr. Peter Marks, FDA’s top vaccine regulator, acknowledged the intense disagreements in opening remarks to the agency’s advisory panel.
“We know there may be differing opinions in interpreting the data,” he said. “We strongly encourage all the different viewpoints to be voiced and discussed regarding the data which is complex and evolving.”
US President Joe Biden’s top health advisers, including the heads of the FDA and CDC, first announced plans for widespread booster shots a month ago, targeting the week of September 20 as an all-but-certain start date. It said boosters would be dispensed eight months after the second dose of the Pfizer and Moderna vaccines.
But that was before FDA staff scientists had completed their own assessments of the data. Some experts questioned whether Biden was breaking his own pledge to “follow the science” on COVID-19 by getting out ahead of government scientists.
Earlier this week, two top FDA vaccine reviewers joined a group of international scientists in publishing an editorial rejecting the need for boosters in healthy people. The scientists said continuing studies show the shots are working well despite the delta variant.
Pfizer was expected Friday to present data suggesting immunity from its vaccine begins to wane somewhere around six to eight months after the second dose.