Moderna releases new data on Covid breakthrough cases it says supports need for booster shots

Moderna on Wednesday released more data on so-called breakthrough cases it says supports the push for wide use of Covid-19 vaccine booster shots.

The U.S. drugmaker shared a new analysis from its phase three study that showed the incidence of breakthrough Covid cases, which occur in fully vaccinated people, was less frequent in a group of trial participants who were more recently inoculated, suggesting immunity for earlier groups had started to wane.

There were 88 identified breakthrough cases out of 11,431 people vaccinated between December and March, the company said in a release, compared with 162 breakthrough cases out of 14,746 trial participants vaccinated in July through October of last year.

There were also fewer severe cases of Covid-19 cases in the group that received the vaccine more recently, according to a manuscript of the results shared by the company. Three Covid-19 related hospitalizations occurred in the group that got the shots early on, resulting in two deaths, according to the data. There were no hospitalizations or deaths in the group that recently received the vaccine, although the finding on severe cases was not statistically significant.

“There’s a large debate, we all know, about whether or not vaccine boosters are going to be necessary into the fall,” Moderna President Stephen Hoge said in a phone interview. “That debate, what makes it really hard is it’s not really about whether the vaccine worked last month. It’s really about whether it’s going to work this winter.”