AstraZeneca insisted that its COVID-19 vaccine provides strong protection even after counting additional illnesses in its U.S. study, as the drugmaker responded to concerns raised by American officials in an unusually public rebuke that threatened to further erode confidence in the shot.
In a late-night news release Wednesday, AstraZeneca said it had analyzed more data from that study and concluded the vaccine is 76% effective in preventing symptomatic COVID-19, instead of the 79% it had reported earlier in the week.
Some experts called the new analysis reassuring and said the updated details didn’t look substantially different from what was announced earlier. A peek at the full data won't come for at least another few weeks, once the Food and Drug Administration begins its own stringent review. For now, it's not clear if the new figures will be sufficient to repair the credibility in a vaccine that, despite being widely used in Britain, Europe and other countries, has had a troubled rollout.
Earlier this week, an independent panel that oversees the U.S. trial of the vaccine had accused AstraZeneca of cherry-picking data to tout the protection offered by its shot. The panel, in a harsh letter to the company and to U.S. health leaders, said AstraZeneca had left out some COVID-19 cases that occurred in the study.
The drugmaker responded that the results it reported included cases up to mid-February, as agreed in the study rules, and that it was preparing a fuller analysis of cases that had occurred since then — which it released Wednesday.
“AstraZeneca may have just been too hasty in submitting the earlier, incomplete interim analysis rather than waiting to analyze and submit the full dataset,” said Julian Tang, a virologist at the University of Leicester who was not connected to the research. He said the updated details were likely solid enough for U.S. regulators to authorize the vaccine.
Before the new results were released, Dr. Anthony Fauci, the top U.S. infectious disease expert, told reporters he hoped that when all the data was publicly vetted by the FDA, it would dispel any hesitancy caused by the spat. He predicted it would “turn out to be a good vaccine.”
AstraZeneca had been counting on findings from a predominantly U.S. study of 32,000 people to help rebuild confidence in its shot, which is crucial to global efforts to end the coronavirus pandemic since it is cheap, easy to store and a pillar of the COVAX initiative aimed at bringing vaccines to low- and middle-income countries. Despite evidence from trials and in real-world use that it does protect, previous studies have turned up inconsistent data about the degree of effectiveness.