Feb. 3 (UPI) -- The COVID-19 vaccine in development by AstraZeneca and Britain's Oxford University has shown in clinical trials to be 76% effective against the coronavirus after 90 days, researchers said Wednesday.
Data from a primary analysis of third-stage trials, published in a manuscript in The Lancet medical journal, showed the vaccine's effectiveness.
The pharmaceutical company said the research also shows the vaccine is 100% effective in preventing severe cases of the coronavirus disease. No trial volunteers died or were hospitalized, either, it said.
The third-phase studies were conducted in Britain, South Africa and Brazil.
"Results demonstrated vaccine efficacy of 76% after a first dose, with protection maintained to the second dose," AstraZeneca said in a statement. "With an inter-dose interval of 12 weeks or more, vaccine efficacy increased to 82%."
"They also detail that a single standard dose of the vaccine is 76% effective at protecting from primary symptomatic COVID-19 for the first 90 days post vaccination, once the immune system has built this protection 22 days after the vaccination, with the protection showing little evidence of waning in this period," Oxford researchers added.
AstraZeneca said the vaccine was studied in about 17,000 volunteers, of which about 300 showed symptoms of COVID-19.
Researchers said the results were similar to other two-dose regimes for vaccines connected with the flu, Ebola and malaria.
"This primary analysis reconfirms that our vaccine prevents severe disease and keeps people out of hospital," Mene Pangalos, executive vice president of BioPharmaceuticals R&D, said.
"Together with the new findings on reduced transmission, we believe this vaccine will have a real impact on the pandemic."
The research published by AstraZeneca and Oxford has not yet been peer reviewed.
The AstraZeneca Oxford vaccine, which has already been approved for use in Britain and the European Union, can be stored and transported at temperatures at 2 degrees Celsius/36-46 degrees Fahrenheit for at least six months -- making it logistically simpler to distribute than the vaccines from Pfizer and Moderna, which always have to be kept at subzero freezing temperatures.
Like the Pfizer and Moderna vaccines, AstraZeneca's consists of a two-dose regimen. Another vaccine developed by Johnson & Johnson is a one-shot dose and can also be shipped and handled at normal refrigerated temperatures.
The Pfizer and Moderna vaccines are the only two that have so far been approved for use against COVID-19 in the United States.