AstraZeneca announced on Monday that its vaccine was 79 percent effective in preventing symptomatic COVID-19 in phase three U.S. testing with no safety concerns found.
The company said in a statement that the vaccine, developed in partnership with Oxford University, was also found to be 100 percent effective in preventing serious cases of the disease and hospitalizations.
AstraZeneca said it will submit the findings to the Food and Drug Administration in a bid for emergency use authorization in the U.S.
The trial involved 32,449 participants and 141 cases of symptomatic COVID-19 were observed.
Participants were given two doses of the vaccine administered four weeks apart, though spacing the shots out longer than four weeks was shown to increase efficacy rates, AstraZeneca noted. Already authorized vaccines from Pfizer and Moderna require two doses, while the Johnson & Johnson inoculation requires one dose.
According to AstraZeneca, vaccine efficacy was consistent across age and ethnicity, though it added that efficacy among people older than 65 was slightly higher, at 80 percent.
The AstraZeneca vaccine can also be stored in normal refrigeration temperatures between 36-46 degrees Fahrenheit. By comparison, Johnson & Johnson’s vaccine is estimated to remain stable for at least three months in most standard refrigerators at temperatures of 36-46 degrees. Pfizer’s vaccine needs to be stored in ultra-cold freezers between minus 112 and minus 76 degrees and Moderna’s vaccine needs to be shipped at between minus 13 and 5 degrees.
The European Union’s top drug regulator announced last week that AstraZeneca’s coronavirus vaccine was safe and effective after more than a dozen countries halted inoculations over concerns of blood clots.
However, the European Medicines Agency also said on Thursday that it could not rule out a link to the blood clots, and said it would add a warning to the product to draw attention to the possibility of such rare side effects.
The Biden administration last week also confirmed plans to send millions of doses of the AstraZeneca COVID-19 vaccine to Mexico and Canada.
“Our first priority remains vaccinating the U.S. population, but the reality is the pandemic knows no borders,” White House press secretary Jen Psaki told reporters on Thursday, saying plans were not finalized. “Ensuring our neighbors can contain the virus is mission critical to ending the pandemic.”
The agreement is not expected to impact President Biden’s plan to make the vaccine available to all U.S. adults by the end of May.
Mexico and Canada will reportedly be expected to pay back the U.S. with doses later this year.
–Joseph Choi contributed to this report, which was updated at 10 a.m.