Moderna: COVID19 vaccine protection wanes, makes case for booster

Several recent studies have suggested that its vaccine may have an edge over a similar shot from Pfizer Inc and German partner BioNTech SE in terms of maintaining efficacy over time.

Experts said the difference is likely due to Moderna's higher dose of messenger RNA (mRNA) and the slightly longer interval between the first and second shots.

Both vaccines proved to be exceedingly effective at preventing illness in their large Phase III studies.

The analysis released on Wednesday, however, showed a chink in the Moderna shot's armor over time, with higher rates of infection among people vaccinated roughly 13 months ago compared with those vaccinated roughly eight months ago. The study has yet to undergo peer review.

Moderna on Sept. 1 submitted its application to the U.S. Food and Drug Administration seeking authorization for a booster shot.

Briefing documents from the FDA's analysis of Pfizer's booster application, released earlier on Wednesday, suggest that a key issue the agency will consider is whether vaccine protection is waning. Previous data on Moderna's shot had shown lasting protection, making the case for boosters more challenging.

In the new analysis, Moderna compared the vaccine's performance in more than 14,000 volunteers vaccinated between July and October of 2020 to some 11,000 volunteers originally in the placebo group who were offered the shot between December 2020 and March 2022 following its U.S. emergency use authorization.

They identified 88 COVID-19 cases among those who got the two shots more recently, compared with 162 cases among those vaccinated last year. Overall, however, only 19 cases were considered severe, a key benchmark in assessing waning protection.

Moderna said there was a trend toward a lower rate of severe cases among the more recently vaccinated, although the finding was not statistically significant.

The company said the waning immunity seen in the new analysis adds to evidence that a booster is needed.

The company also highlighted two studies showing long-lasting protection against severe disease.

In a study conducted with Kaiser Permanente Southern California while the highly transmissible Delta variant was circulating, researchers found the Moderna vaccine was 87% effective at preventing a COVID-19 diagnosis, and 96% effective at preventing hospitalization.

They had analyzed data on more than 352,000 people who got two doses of the Moderna vaccine compared with the same number of unvaccinated individuals with similar ages and risk factors.