Pfizer makes case for fourth COVID jab dose to FDA

Earlier this week, Pfizer chief executive Albert Bourla said that a second booster of its COVID-19 vaccine will be necessary to keep the pandemic under control, and the company has now asked the FDA to back this use.

The company and partner BioNTech have filed for emergency use authorisation of a fourth dose of Comirnaty based on real-world safety and efficacy data from Israel, where a fourth dose has been authorised for people aged 60 and over and those in high-risk groups.

The results showed that rates of confirmed infections after a second booster were two times lower and rates of severe illness four times lower compared to people who had received one booster of any of the authorised COVID-19 vaccines, said Pfizer.

The real-world data comes from an analysis of health records from 1.1 million people in Israel eligible for a second booster, who got a Comirnaty shot at least four months after an initial booster, at a time when the Omicron variant was already in wide circulation.

Pfizer and BioNTech's filing also included data from an open-label study in Israel involving healthcare workers aged 18 and over, including 154 who had received Comirnaty as a second booster and 120 who received Moderna's SpikeVax.

The results showed a seven- to eight-fold increase in neutralising antibodies to SARS-CoV-2, restoring them to levels seen after a third dose but not raising them higher, suggesting the vaccines had reached an upper limit.

The researchers also note that a fourth dose with either of the mRNA vaccines showed "low activity in preventing mild or asymptomatic Omicron infections."

A co-author of the study – Gili Regev-Yochay of Sheba Medical Center in Ramat Gan – told the journal Nature that while a third dose is very important, people who are young and healthy without risk factors "will probably not benefit much from a fourth dose."

Bourla said in an interview with CBS on Sunday that the protection with current vaccine doesn't last very long so a fourth dose will be needed to keep hospitalisations and severe cases of COVID-19 at bay, but acknowledged that next-generation vaccines will be needed.

He said Pfizer is working on vaccines that will offer protection against all variants of COVID-19, as well as provide a longer duration of protection of "at least a year."