In a separate move aimed at answering longer term questions about booster strategies, the FDA plans to convene its outside advisers in early April to consider whether there should be an October or November campaign to encourage some or all adults to get additional boosters and whether the shots should be the same as the current vaccine or retooled to counter new variants, according to a federal official who spoke on the condition of anonymity to discuss administration plans.
The official said: “Would it make sense to have some kind of a booster campaign for all or a segment of the population in the fall to prevent a wave of infections” as the weather gets cold again?
Increasingly, some officials have signaled they believe adults of all ages might need a second booster because of the lack of durability of the two-shot mRNA vaccines made by Pfizer-BioNTech and Moderna.
Albert Bourla, chief executive officer of Pfizer, has said in recent days he believes a second booster will be needed for everyone. At a Washington Post Live event last week, Bourla said a fourth shot would be needed because immunity wanes.
“We are working right now very intensively. … I think our data suggests that they [a fourth dose] are protecting — they are improving dramatically the protection, the fourth dose compared to the third for omicron after some time, after, let’s say, three to six months,” Bourla said.
He told CBS’s “Face the Nation” in an interview that aired Sunday that a fourth dose would be “necessary.” He said the protection provided by the first booster is “actually quite good for hospitalizations and deaths. It’s not that good against infections.” Pfizer and BioNTech are working on a vaccine that will work against all variants and provide protection for at least a year.
Pfizer spokeswoman Jerica Pitts declined to confirm the possible emergency authorization filing and said the company was “continuing to collect and assess all available data and we’re in continuous, open dialogue with regulators and health authorities to help inform a COVID-19 vaccine strategy as the virus evolves.”
The FDA declined to comment.
In a recent interview, Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, said U.S. data so far shows protection against severe illness remains robust four to five months after a booster — falling somewhat from 91 percent effective in preventing severe illness to 78 percent effective.
“The proof in the pudding is how long protection following a third boost lasts — five, six, seven, eight months out,” Fauci said. “If it goes down, then you make your decision about whether you’re going to boost based on the clinical data.”
It is not clear what the Israeli data Pfizer will submit for its application seeking a second booster for people 65 and older shows, but inside the Biden administration, officials are looking for clarity on two fronts. They want to see the extent to which immunity wanes after the first booster shot and the efficacy of a second booster shot. Some preliminary data on the effects of a fourth dose have been made available from Israel, where a fourth dose has been used in people 60 and older, health-care workers and immunocompromised people. Some of that data has been mixed.
One study, published on a preprint server before peer review, tracked infections and hospitalizations in Israel in the second half of January, after a fourth dose began to be offered. In people 60 and older who received a fourth shot, rates of infection were lower after the fourth dose. The rates of severe illness were substantially lower in people who received a fourth shot.
“Giving the fourth dose to individuals who were at risk to develop severe disease has been instrumental in limiting the burden on hospitals in Israel during the fast and wide-spreading Omicron surge,” the researchers concluded.
But a separate preprint study from Israel that tested a fourth shot in health-care workers found a mixed picture. A fourth shot of the PfizerBioNTech or Moderna shot increased virus-fighting antibodies but was not very effective at preventing mild or asymptomatic infections. That suggests that as a longer-term strategy — and for people who are not at high risk of severe disease — a fourth shot may not be the ideal way to increase immunity. Breakthrough infections were common, and people had large amounts of virus in their noses, suggesting they could infect others.
Pfizer and BioNTech are also formally testing a fourth shot in a clinical trial that began in January. In one group of 600 fully vaccinated and boosted people, they are comparing a version of their vaccine fine-tuned to fight the omicron variant to a fourth shot of the regular vaccine.
The American public — and even experts — have been sharply divided on coronavirus vaccines and boosters, with the United States falling far short of vaccination rates seen in many other countries. Pfizer’s announcement that a third shot would be needed last summer helped sow some of that confusion. The company got pushback from government officials, who had not yet been persuaded one was needed, although they later called for them.
Now, with some studies showing that vaccine effectiveness has ebbed to some extent in the face of the highly contagious omicron variant, some older people have been clamoring for a second booster — or getting one even before it is officially authorized.
But other individuals, of all ages, appear to have little interest in the shots, especially as the omicron threat fades and infections and hospitalizations plunge.
Officials in the Biden administration and the public health community are keeping a close eye on a rise in covid-19 cases in Europe and the proliferation of the omicron variant BA.2. Some experts are worried there could be an increase in cases in the United States following the relaxation of mask requirements as BA.2, which is more transmissible than the original version of omicron, becomes dominant.
A study published last month in the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report suggested boosters of Pfizer-BioNTech and Moderna vaccines lost some effectiveness after four months but still offered strong protection against severe illness and hospitalization. The study said the vaccine appeared to be more effective against the earlier delta variant than the omicron variant.
In January, Israel began offering a fourth dose of the Pfizer-BioNTech vaccine to people 60 and older and medical workers. In France, second boosters are available for everyone 80 and older, and people who are immunocompromised or have a long-term illness. Chile and Germany also are recommending fourth shots for high-risk groups.
In the United States, four shots of the vaccine are already authorized for people who have moderately or severely compromised immune systems, which hinder an effective response to the vaccine.