AstraZeneca’s experimental COVID-19 vaccine is the third vaccine to demonstrate it can prevent coronavirus infections in a late-stage clinical trial, though the viral vector-based vaccine is much less efficacious than the other leading vaccine candidates.
The British drug maker, which is developing the vaccine with the University of Oxford, said the vaccine had an efficacy rate of 90% in a small subset of about 2,700 participants in Brazil and the U.K. who received a half dose and then a full dose four weeks later, according to an interim analysis. A larger group of nearly 8,900 participants produced an efficacy rate of 62% when given two full doses, spaced a month apart.
The average efficacy rate for this vaccine is significantly lower than the roughly 95% efficacy rates reported last week for BioNTech
and Pfizer Inc.’s
investigational vaccine, BNT162b2, and Moderna Inc.’s
mRNA-1273 — both of which are messenger ribonucleuc acid, or mRNA, vaccines.
(None of these drug makers have yet published clinical data for the vaccines’ performance in late-stage clinical trials in peer-reviewed medical journals, which is considered the gold standard when it comes to sharing medical research. They so far have only shared interim data points.)
AstraZeneca’s decision to include two efficacy rates was criticized by one Wall Street analyst as insufficient. However, the inclusion of the smaller subset with a higher efficacy rate may indicate a company strategy to push this vaccine to markets in less developed countries. They “are clearly already positioning the product as suitable for use in less developed countries, where their relatively favorable storage conditions…may be advantageous,” SVB Leerink’s Geoffrey Porges wrote in an investor note on Monday. “We believe that this product will never be licensed in the U.S.”
Of the handful of vaccines that have moved into late-stage clinical studies in the U.S., there are a number of notable differences between all of them.
An mRNA vaccine has never received any type of regulatory approval, and the ones being tested right now have refrigeration requirements that will likely impact how easily a vaccine can be distributed. Viral vector-based vaccines, like AstraZeneca’s ChAdOx1 and Johnson & Johnson’s
Ebola virus vaccine, have been around for decades and do not have the same level of cold-storage requirements.
The global race to develop a COVID-19 vaccine also carries economic weight for nations, as developed countries like the U.S. and parts of Western Europe that have failed to limit outbreaks with social distancing look to vaccination as the primary solution to the pandemic.
“A vaccine’s profile can impact how quickly a country emerges from COVID19 — those which can afford to wait for a stronger option may be well served by doing so,” Evercore ISI analyst Josh Schimmer told investors on Monday. “Rushing to take a ‘less than’ option might only delay recovery. In which case, ChAdOx1 is not the way to go.”
BioNTech and Pfizer last week filed for an emergency use authorization, putting their vaccine candidate at the front of the line to potentially receive marketing authorization in the U.S. A Food and Drug Administration advisory committee is scheduled to meet Dec. 10 to discuss the risks and benefits of BNT162b2.
AstraZeneca’s stock has gained 8.9% so far this year, while the S&P 500
is up 10.1%.