AstraZeneca's error in the dosing regimen of its coronavirus vaccine, which showed higher efficacy results, though fortuitous, might lead to an overall revision of clinical trials, George Rutherford, a professor of epidemiology and biostatistics at the University of California-San Francisco, told Sputnik
MOSCOW (Pakistan Point News / Sputnik - 26th November, 2020) AstraZeneca's error in the dosing regimen of its coronavirus vaccine, which showed higher efficacy results, though fortuitous, might lead to an overall revision of clinical trials, George Rutherford, a professor of epidemiology and biostatistics at the University of California-San Francisco, told Sputnik.
On Monday, AstraZeneca released interim test results of its candidate vaccine showing two different levels of efficacy depending on the dosing regimen. Efficacy in patients administered two full doses one month apart was 62 percent, while in those administered a half-dose and then a full dose it reached 90 percent. The company later admitted that the regimen with higher efficacy had actually been a result of a dosing mistake.
"While the mistake may be fortuitous, it raises questions about the trial overall, which will need to be carefully reviewed," Rutherford said.
The success of a vaccination sequence from a lower to a higher dose makes sense from the scientific point of view, according to the immunologist. The immune system's initial encounter with an easy amount of virus makes it better prepared for the future battle with a larger amount.
Rutherford believes that if the AZD1222 vaccine indeed proves 90 percent effective, it will likely make strong competition for rival candidate vaccines thanks to its price and more flexible storage requirements.
Still, the diverging clinical trial results have shaken the confidence in the vaccine, especially given that the dosing error has not been mentioned in any of the developers' earlier official press releases. AstraZeneca Executive Vice President Mene Pangalos said the mistake was only discovered when the company checked its vaccine stocks after noticing inconsistencies in the participants' inflammatory reactions.
Moncef Slaoui, the chief adviser of US vaccine facility US Operation Warp Speed, has pointed out that the regimen with higher efficacy had only been administered on participants younger than 55 years of age. This batch of participants was also much smaller in size than the one that received two full doses 2,741 and 8,895, respectively.
AstraZeneca and the University of Oxford, the vaccine's co-developer, now plan to test the more effective reduced dosing regimen on 30,000 volunteers in the United States.
