LONDON – AstraZeneca’s repeated missteps in reporting vaccine data coupled with a blood clot scare could do lasting damage to the credibility of a shot that is the linchpin in the global strategy to stop the coronavirus pandemic, potentially even undermining vaccine confidence more broadly, experts say.
The latest stumble for the vaccine came Tuesday, when American officials issued an unusual statement expressing concern that AstraZeneca had included “outdated information” when it reported encouraging results from a U.S. trial a day earlier. That may have provided “an incomplete view of the efficacy data,” according to the statement.
AstraZeneca responded that the results, which showed its shot was about 79% effective, included information through Feb. 17 but appeared to be consistent with more up-to-date data. It promised an update within 48 hours.
An independent panel that oversees the study scolded the company in a letter Monday for cherry-picking data, according to a senior administration official. The panel wrote to AstraZeneca and U.S. health leaders that it was concerned the company chose to use data that was outdated and potentially misleading instead of the most recent findings, according to the official, who discussed the contents on the condition of anonymity given the sensitivity of the matter.
“This will likely cause more vaccine hesitancy,” said Dr. Paul Hunter, a professor of medicine at the University of East Anglia.
Even if the damage is limited to AstraZeneca itself, it would have far-reaching effects since the shot is cheaper and easier to store than many of its rivals’ and thus is expected to be widely used in the developing world. International health agencies have repeatedly said the vaccine is safe and effective, but it’s not the first time the company has run into problems with public trust.
Partial results from its first major trial — which Britain used to authorize the vaccine — were clouded by a manufacturing mistake that researchers didn't immediately acknowledge. Insufficient data about how well the vaccine protected older people led some countries to initially restrict its use to younger populations before reversing course. U.S. officials suspended an AstraZeneca study for an unusual six weeks while they sought details about problems reported in Britain before deciding the vaccine wasn't to blame. Meanwhile, the European Union has complained about delays in vaccine deliveries from the company.
Then last week, more than a dozen countries temporarily halted their use of the AstraZeneca shot after reports of rare blood clots in some people who received it. The European Medicines Agency concluded the shot did not increase the overall incidence of clots, but the unwanted attention appears to have left a mark.