The announcement this week that a cheap, easy-to-make coronavirus vaccine appeared to be up to 90 percent effective was greeted with jubilation. “Get yourself a vaccaccino,” a British tabloid celebrated, noting that the vaccine, developed by AstraZeneca and the University of Oxford, costs less than a cup of coffee.
But since unveiling the preliminary results, AstraZeneca has acknowledged a key mistake in the vaccine dosage received by some study participants, adding to questions about whether the vaccine’s apparently spectacular efficacy will hold up under additional testing.
Scientists and industry experts said the error and a series of other irregularities and omissions in the way AstraZeneca initially disclosed the data have eroded their confidence in the reliability of the results.
Officials in the United States have noted that the results were not clear. The head of the flagship federal vaccine initiative suggested that the vaccine’s most promising results may not have reflected data from older people.
The regimen that appeared to be 90 percent effective was based on participants receiving a half dose of the vaccine followed a month later by a full dose; the less effective version involved a pair of full doses. AstraZeneca disclosed in its initial announcement that fewer than 2,800 participants received the smaller dosing regimen, compared with nearly 8,900 participants who received two full doses.
The biggest questions were, why was there such a large variation in the effectiveness of the vaccine at different doses, and why did a smaller dose appear to produce much better results? AstraZeneca and Oxford researchers said they did not know.
Crucial information was also missing. The company said that the early analysis was based on 131 symptomatic Covid-19 cases that had turned up in study participants. But it did not break down how many cases were found in each group of participants — those who received the half-strength initial dose, the regular-strength initial dose and the placebo.
Adding to the confusion, AstraZeneca pooled the results from two differently designed clinical trials in Britain and Brazil, a break from standard practice in reporting the results of drug and vaccine trials.
In the statement attributed to Oxford, Ms. Meixell, the AstraZeneca spokeswoman, said the error stemmed from an issue, which has since been fixed, with how some of the vaccine doses were manufactured.
Then, on Tuesday, Moncef Slaoui, the head of Operation Warp Speed, the U.S. initiative to fast-track coronavirus vaccines, noted another limitation in AstraZeneca’s data. On a call with reporters, he suggested that the participants who received the half-strength initial dose had been 55 years old or younger. Ms. Meixell declined to say whether that was the case, noting that the data would be published soon in a peer-reviewed journal.
Scientists are also pressing the Oxford team to start a fresh, large-scale trial focused solely on determining whether the half-dose regimen was indeed more effective than the two standard doses.
https://www.nytimes.com/2020/11/25/business...rxecRK-tBHvPJzEGood news for vaccine haters
