After results are questioned, AstraZeneca says complete data shows vaccine still highly effective

AstraZeneca reiterated Wednesday that its COVID-19 vaccine was very effective at preventing the disease, based on more recent data than was included when the company announced the interim results of its US clinical trial on Monday.

The company said in a news release that its vaccine was 76% effective at preventing COVID-19. That is slightly lower than the efficacy number that the company announced earlier this week.

The new results strengthen the scientific case for the embattled vaccine. But they may not repair the damage to AstraZeneca’s credibility after US health officials and independent monitors issued an extraordinary rebuke of the company for not counting some COVID-19 cases when it announced its initial findings this week.

In a news release Wednesday, the company said complete results from its 32,000-person study showed that its vaccine was 76% effective. On Monday, the company said the vaccine appeared to be 79% effective, based on an interim look at 141 COVID-19 cases that had turned up among volunteers before Feb. 17. The latest finding was based on 190 trial participants who had gotten sick with COVID-19.

AstraZeneca said on Wednesday that the vaccine was 100% effective in preventing severe disease and 85% effective in preventing COVID-19 in people over age 65.

When it unveiled its interim results Monday, AstraZeneca ignored dozens of recently confirmed COVID-19 cases that had cropped up in trial volunteers before mid-February.

In a letter to the company and federal officials, the independent monitoring board that was helping oversee the clinical trial issued an unusual reprimand of AstraZeneca for appearing to cherry-pick data to make its vaccine appear more effective.

It was not clear why the monitoring board’s projection turned out to be lower than the figure in AstraZeneca’s complete results. The results could change again, because there are 14 possible COVID-19 cases that AstraZeneca representatives have not yet classified as actual cases.

Until they received the monitoring board’s letter, AstraZeneca executives weren’t aware that the panel expected them to include those cases in the results disclosed in their news release, according to a person familiar with the executives’ thinking.

© 2021 New York Times News Service