Pfizer asks FDA to authorize second booster for adults 65 plus
Pfizer and BioNTech on Tuesday asked the Food and Drug Administration (FDA) for emergency use authorization for a second booster shot of their coronavirus vaccine for adults age 65 and older.
The companies said there's emerging evidence that the vaccine's effectiveness against symptomatic infection and severe disease caused by the omicron variant wanes three to six months after receipt of an initial booster dose.
As a result, the companies said a second booster administered at least four months after an initial booster dose could restore antibody levels to peak post-third dose level.
The additional dose for older Americans would bolster that waning immunity. Adults over age 65 are among the most vulnerable to severe COVID-19 infection, even with vaccinations.
Booster shots are currently authorized for everyone 12 and older on an emergency use basis. The FDA has fully approved the initial two doses of the Pfizer COVID-19 vaccine.
According to the companies, the submission is based on two real-world data sets from Israel analyzed at a time when the omicron variant was widely circulating. Israel is one of the only countries that has authorized a fourth dose of the vaccine.
One study, posted to a preprint server in February, tracked infections of 1.1 million people over the age of 60, and found rates of confirmed infections were two times lower among individuals who received a second booster dose at least four months after the initial booster. Rates of severe illness were four times lower.
The companies also included a second Israeli study that tested an additional booster dose of both Pfizer and Moderna's vaccine in healthcare workers 18 years of age and older. According to a preprint of the study, there was a noticeable increase in neutralizing antibodies, especially against omicron.
While the study revealed no new safety concerns, the booster was not effective at preventing symptomatic infection, and breakthrough infections were common. Pfizer's vaccine was 30 percent effective against infection, and Moderna's was only 11 percent. People also were observed to have large viral loads, even with mild infections, meaning they could easily spread the virus to others.
The mixed results are likely to reignite debate about the effectiveness of booster shots, and the Biden administration's booster strategy.
Before the omicron variant began spreading and evidence showed a large drop in immunity, many health experts questioned the effectiveness of booster shots in younger healthy people.
Part of the debate centered on whether the goal is to prevent people from being hospitalized with COVID-19 or whether the goal is to prevent them from getting sick at all, even if it is milder.
The news comes days after Pfizer CEO Albert Bourla said another booster shot will be necessary.
"Right now, the way that we have seen, it is necessary, a fourth booster right now. The protection that you are getting from the third, it is good enough, actually quite good for hospitalizations and deaths," Bourla said on CBS's "Face the Nation."
"It's not that good against infections but doesn't last very long. But we are just submitting those data to the FDA [Food and Drug Administration], and then we will see what the experts also will say outside Pfizer," he added.
Pfizer's request also comes as COVID-19 cases have been falling in the U.S. and the Centers for Disease Control and Prevention said most areas in the U.S. no longer need mask mandates indoors.
Updated at 7:04 p.m.
