Adjusted AstraZeneca data shows COVID-19 vaccine 76 percent effective

AstraZeneca released updated data on its COVID-19 vaccine, saying a more recent analysis shows the vaccine is 76 percent effective against symptomatic COVID-19. It’s a slight drop from the 79 percent the company touted in an announcement earlier this week. That number was based on outdated data, US health officials said in an unusual public statement rebuking the company.

The original efficacy was based on an interim analysis using data collected until February 17th. But adding more data collected after that date showed that the vaccine may have been 69 to 74 percent effective, according to a letter from the independent panel monitoring the clinical trial and reported by The Washington Post. The panel “strongly recommended” those numbers also be reported.

The new result is a few percentage points higher, but a finding in that range would have still been a good result and much higher than the 50 percent efficacy cutoff the US Food and Drug Administration said it wanted from COVID-19 vaccines last fall. A federal official told The Washington Post that AstraZeneca’s decision to publish only the higher number earlier this week was like “telling your mother you got an A in a course, when you got an A in the first quiz but a C in the overall course.”

Releasing scientific data in a press release instead of in a scientific paper means that outside experts can’t scrutinize the claims. The companies behind the first three COVID-19 vaccines authorized for use in the United States also first reported the results of their clinical trials in press releases. Their data held up, but experts were still critical of that strategy. The botched AstraZeneca data release shows why they were so cautious.

The updated data indicated that, likelier than not, this vaccine is a good vaccine, and it will have a major role to play in the world’s fight against COVID-19. It’s cheap compared to the Moderna and Pfizer / BioNTech vaccines, it can be stored at room temperature, and it’s been earmarked as the main shot to vaccinate lower-income countries.

But for the past year, it’s been defined more by controversy than good science. The company wasn’t transparent with regulators when the trial had safety issues, for example, and its clinical trial had mistakes and opaque methodology. The US clinical trial was supposed to clear up the confusion. Instead, the botched data release added to the mess just as public health officials are trying to shore up confidence in COVID-19 vaccines.

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