BOSTON (CBS) – The drug maker AstraZeneca has revised its analysis of a large clinical trial involving its new COVID-19 vaccine and it may not be as effective as initially reported.

The company now says its vaccine is 76% effective against symptomatic COVID-19 versus the 79% they reported earlier this week.

AstraZeneca made the correction after U.S. health officials criticized the company for not using the most up-to-date information when initially crunching the numbers in their clinical trial.

While the vaccine appears slightly less effective in preventing symptomatic COVID-19 than originally reported, an effectiveness of 76% is still impressive and the company maintains that it was still 100% effective at preventing severe disease and hospitalization and 85% effective at preventing symptoms in people 65 and older.

Dr. Mallika Marshall