AstraZeneca may conduct an additional global trial of its COVID-19 vaccine candidate following scrutiny from many scientists over results released last week, Bloomberg reported.
The drugmaker had reported that its vaccine was up to 90 percent effective in preventing COVID-19 infection. But it later said a manufacturing error resulted in some clinical trial participants receiving only half the intended dose of the vaccine, The New York Times reported.
AstraZeneca CEO Pascal Soriot has proposed conducting an additional trial to confirm the 90 percent efficacy rate, according to Bloomberg. The trial could be faster because it needs a smaller number of participants, and Mr. Soriot said he doesn't expect the trial to stall regulatory approvals of the vaccine in the U.K. and European Union.
The 90 percent efficacy rate was shown in participants who received the half dose of the vaccine initially, followed a month later by a full dose. In participants who received two full doses, the vaccine was only 62 percent effective. Fewer than 2,800 participants received the half-dose regimen, compared to 8,900 who received the full dose. Researchers said they don't know why there was such a large variation in effectiveness and why the smaller dose appears to produce better results, the Times reported.
AstraZeneca also pooled the results from two differently designed clinical trials in Britain and Brazil, which isn't standard practice when reporting drug and vaccine trial results. Scientists told the Times that AstraZeneca's omissions in its data have eroded their confidence in the vaccine results.