A vaccine jointly developed by Oxford University and AstraZeneca (LON:AZN) recently won authorization in the U.K. Meanwhile, health officials in Turkey and Brazil have indicated that a vaccine from the Chinese firm Sinovac is safe and effective.
But one factor that could slow the deployment of both vaccines globally is confusing clinical trial results. Sinovac’s CoronaVac product has an efficacy rate of anywhere from 50% to 90%, according to a Brazilian study. Turkish officials meanwhile determined the vaccine to be 91.25% effective against COVID-19 based on preliminary results from a small study.
Similarly, the AstraZeneca-Oxford vaccine’s efficacy ranges from 62% to 90%, depending on the dosing regimen, according to a Phase 3 interim analysis. The average efficacy in the trial was 70%.
In the absence of building momentum for COVID-19 vaccines from Pfizer (NYSE:PFE) and Moderna (NYSE:MRNA), the unclear data would be unlikely to curb demand for vaccines that stem the tide of a worsening pandemic. But the vaccines from Pfizer and Moderna have the advantage of clear data. Both vaccines from those companies have an efficacy of approximately 95% based on Phase 3 trials involving tens of thousands of volunteers.
The data associated with the SinoVac and AstraZeneca vaccines, by contrast, is more ambiguous.
Brazilian authorities did not release detailed data from clinical trials owing to a contractual agreement. More data, however, is forthcoming by Jan. 7.
U.K. medical authorities are reviewing final data from a clinical trial from AstraZeneca and Oxford University.
Note: This article was updated to on Jan. 4 to reflect that the AstraZeneca vaccine has been authorized in the U.K.