Covid-19 vaccine found a higher rate of breakthrough cases in people who got shots early in the study. The analysis, detailed in a news release from Moderna on Wednesday, examined instances where immunized people in the company’s trial still contracted Covid-19 this summer, when the delta variant was surging.
In Moderna’s trial, people who first received a placebo were offered the vaccine starting in December, after initial positive efficacy results were reported.
That created a group who were immunized a median of five months later than those who got the vaccine from the start of the study.
The company said it found that people who received the vaccine earlier had more than a 50% higher rate of symptomatic breakthrough infections in