The companies said their submission is based on two real-world data sets from Israel analyzed at a time when the Omicron variant was widely circulating. Both showed evidence that an additional mRNA booster increases immunogenicity and lowers rates of confirmed infections and severe illness.

Submissions to pursue regulatory approvals in those countries where emergency use authorizations or equivalent were initially granted are planned, the companies said.

According to the Israeli data, the rates of confirmed infections were two times lower and rates of severe illness were four times lower among individuals who received an additional booster dose of the Pfizer-BioNTech Covid-19 vaccine administered at least four months after an initial booster (third) dose compared to those who received only one booster dose.

Also as part of their submission, the vaccine partners included results from an ongoing, open-label, non-randomized clinical trial in healthcare workers 18 years of age and older at a single study center in Israel who had been vaccinated with three doses of the Pfizer-BioNTech Covid-19 Vaccine.

The Israeli results are said to have shown that the increase in antibody titers lasted longer after a fourth dose than after a third dose. Pfizer and BioNTech also said the Israeli studies revealed no new safety concerns in individuals who received an additional booster dose of the vaccine.

Comirnaty is currently authorized by the FDA as a single booster dose administered at least five months after completion of a primary series in individuals 12 years of age and older. A single booster dose can also be administered to individuals 18 years of age and older who have completed primary vaccination with another authorized or approved Covid-19 Vaccine.

But while Pfizer CEO Albert Bourla has taken its case for a fourth dose for all age groups to US media, in a number of for the most part televised interviews, the other US company with an RNA-based Covid vaccine has initially been more reticent.

In an interview with the web-based Business Insider newsletter, Moderna’s president, Stephen Hoge, said the vaccine maker is recommending a fourth dose for those who are immune-compromised or older adults, aged 50  or at least 65. For everyone else, a fourth dose “should be left as a matter of choice,” Hoge said. 

Author: Dede Williams, Freelance Journalist