New Moderna Vaccine Data 'Support' Booster Shot After 8 Months

Damian McNamara

September 15, 2021

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Moderna released new data today that it said support the argument for COVID-19 booster shots — specifically showing that people who received a first shot of their mRNA vaccine a median of 13 months ago are more likely to experience a breakthrough infection compared to individuals who received a first shot a median of 8 months ago.

The findings come from the ongoing Phase 3 COVE clinical trial, the results of which the US Food and Drug Administration (FDA) considered in granting emergency use authorization for the vaccine. In the initial stage of the trial, people were randomly assigned to receive the company's mRNA vaccine or placebo.

Participants in COVE who were immunized more recently were 36% less likely to experience a breakthrough infection, according to the analysis of the open-label extension of the study during which placebo participants could cross over and get immunized as well.  

The updated COVE trial data show that 88 breakthrough cases of COVID-19 occurred among 11,431 participants vaccinated December 2020 to March 2021 (49.0 cases per 1000 person-years).

In contrast, there were 162 breakthrough cases among 14,746 people vaccinated July to October 2020 (77.1 cases per 1000 person-years).

The breakthrough infections include 19 severe cases. Although not statically different, there was a trend toward fewer severe cases among the more recently vaccinated, at a rate of 3.3 per 1000 person-years, compared with 6.2 per 1000 person-years in the group vaccinated last year.

The findings were posted as a preprint to the medRxiv server and have not yet been peer reviewed.

"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," Moderna Chief Executive Officer Stéphane Bancel said in a company statement.

An FDA advisory committee is meeting Friday to look at the available evidence on boosters to help the agency decide whether the additional shots are warranted.

There is still a lot of debate in the medical community about the need for boosters. US physicians and nurses are divided about the need for them and about how the country should prioritize its vaccine supplies, according to a Medscape poll of more than 1700 clinicians that collected responses from August 25 to September 6, 2020.

The research was funded by Moderna, and also supported by the Office of the Assistant Secretary for Preparedness and Response, Biomedical Advanced Research and Development Authority and by the National Institute of Allergy and Infectious Diseases.

Damian McNamara is a staff journalist based in Miami. He covers a wide range of medical specialties, including infectious diseases, gastroenterology and critical care. Follow Damian on Twitter: @MedReporter.

Follow Medscape on Facebook, Twitter, Instagram, and YouTube.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.