Does The COVID Vaccine Last? Moderna Says Booster Will Be Needed

Moderna released new data Wednesday supporting the use of COVID-19 vaccine booster shots.

The data, which has not yet been peer-reviewed, came after the U.S. drugmaker conducted a large vaccine trial on breakthrough cases among vaccinated people. It revealed that those who were vaccinated a year ago had 36% more breakthrough infections compared to those who were vaccinated about six months ago, suggesting that protection waned over time.

"This is only one estimate, but we do believe this means as you look toward the fall and winter, at minimum we expect the estimated impact of waning immunity would be 600,000 additional cases of COVID-19," Moderna President Stephen Hoge said in a conference call with investors.

More than 14,000 people were randomly assigned to participate in this Phase 3 of Moderna’s study. Of the 11,431 trial participants vaccinated between December and March, 88 were breakthrough cases. Meanwhile, 162 of the 14,746 people vaccinated between July and October of last year were breakthrough cases.

In a phone interview with CNBC, Hoge touched on the complexity of booster shots. He said it is “not really about whether the vaccine worked last month. It’s really about whether it’s going to work this winter.”

On Sept. 1, Moderna submitted an application to the Food and Drug Administration requesting authorization of its booster shot, Reuters noted.

"We believe this will reduce COVID-19 cases," Hoge said. "We also believe that a third dose of mRNA-1273 has a chance of significantly extending immunity throughout much of next year as we attempt to end the pandemic."