Moderna released data Sept. 15 showing that breakthrough COVID-19 cases were less common in people vaccinated about eight months ago compared to those vaccinated more than a year ago in clinical trials.
In the drugmaker's analysis from a phase 3 study, 88 breakthrough cases occurred in the group of participants vaccinated a median of eight months ago, compared to 162 cases in the group vaccinated a median of 13 months ago.
There were fewer severe cases of COVID-19 in the group vaccinated more recently, Moderna said. Three hospitalizations and two deaths occurred in the group that got the shots longer ago, while no hospitalizations or deaths occurred in the group vaccinated more recently. The drugmaker said the difference in the number of severe cases between groups wasn't statistically significant.
Moderna argued the data supports the authorization of booster shots in the general population, as it shows that efficacy of the vaccine likely wanes over time.
"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. We hope these findings are helpful as health authorities and regulators continue to assess strategies for ending this pandemic," Moderna CEO Stéphane Bancel said in a news release.
Moderna's analysis has not been peer reviewed.
The FDA's vaccine advisory panel is set to meet Sept. 17 to discuss booster shots of Pfizer's vaccine in the general population.
A separate study Moderna released Sept. 15 showed that the drugmaker's vaccine was 87 percent effective at preventing COVID-19 during the emergence of the delta variant. The study was conducted with Oakland, Calif.-based Kaiser Permanente and compared 352,878 vaccinated people to the same number of unvaccinated people. The shot was also 96 percent effective against hospitalization.
Find Moderna's full news release here.