AstraZeneca revises Covid vaccine data with lower efficacy rate after accuracy questions

AstraZeneca issued updated phase three trial data for its Covid-19 vaccine on Wednesday after facing accuracy questions earlier this week surrounding a preliminary report from its U.S. study. The company now says its vaccine is 76% effective in protecting against symptomatic cases of virus. A release issued on Monday reported a symptomatic efficacy rate of 79%. The updated report maintains that the shot is 100% effective against severe disease and hospitalization.

A slate of U.S. health officials criticized the company in recent days for what some claimed was data cherry-picking in an effort to make the results appear more favorable. The National Institute of Allergy and Infectious Diseases revealed on Tuesday it had been informed the U.K.-based company may have included information from its U.S. results that provided an “incomplete view of the efficacy data.”

The updated results include data collected from 190 symptomatic cases, across more than 32,000 participants — an increase of roughly 50 symptomatic cases studied compared with the data set released on Monday. The findings suggest the vaccine is more effective in patients aged 65 and older than previously understood, with a newly reported efficacy rate of 85% for that population, up from a previously stated 80%. AstraZeneca reiterated Wednesday that the vaccine was “well tolerated” among participants and that no safety concerns were identified.

AstraZeneca revises Covid vaccine data with lower efficacy rate after accuracy questions, CNBC, Mar 25