Moderna announced on Wednesday new data supporting COVID-19 booster shots, noting a higher risk of breakthrough infections and observed waning immunity among people who received their first vaccine dose earlier.
In a trial called COVE, there were 88 breakthrough infections among 11,431 participants, or 59 cases per 1,000 person-years, who received their first shot of the mRNA vaccine between December and March. Among 14,746 participants who received their first dose between July and October 2020, 162 of them experienced a breakthrough infection, which is a rate of 77.1 cases per 1,000 person-years. Participants vaccinated more recently had a 36% lower incidence rate versus those who got inoculated earlier, Moderna’s analysis found.
The trial researchers only observed 19 severe breakthrough infections and noted a lower rate of serious cases for the group vaccinated more recently, 3.3 per 1,000 person-years compared to 6.2 per 1,000.
“The increased risk of breakthrough infections in COVE study participants who were vaccinated last year compared to more recently illustrates the impact of waning immunity and supports the need for a booster to maintain high levels of protection,” said Stéphane Bancel, CEO of Moderna, in a statement. We hope these findings are helpful as health authorities and regulators continue to assess strategies for ending this pandemic.”
The results come from the ongoing phase three trial that the U.S. Food and Drug Administration examined when it granted Moderna emergency use authorization for its vaccine. Participants of the trial were assigned randomly to either receive a placebo or Moderna’s coronavirus vaccine.
Moderna posted the findings as a preprint to the medRxiv server. The study has not yet been peer-reviewed.
Data from Pfizer’s application for booster doses released on Wednesday also found that the occurrence of breakthrough cases was higher among people who got their second COVID-19 shot earlier, at least eight months before July, compared to those who received their second dose less than four months before July.
“The totality of the available data supports the public health need for a booster (third) dose of BNT162b2 at approximately 6 months after the second dose of BNT162b2 for individuals 16 years of age and older,” Pfizer said in its application to the FDA.
Pfizer said its data shows that a third dose of its vaccine administered about six months after the second dose had an “acceptable safety profile and elicited robust immune responses” against the original coronavirus and the Beta and Delta strains. The vaccine maker also cited data from Israel that found that a booster dose of its vaccine restored high levels of protection against COVID-19, back up to about 95% effectiveness.
An FDA advisory committee is set to meet Friday to review the data on boosters and to decide whether the extra shots are needed.