Drugmaker AstraZeneca's coronavirus vaccine candidate was found to have 70.4% efficacy in an interim analysis of Phase 3 trial results, published for the first time in a peer-reviewed journal.
The findings fall in line with the efficacy that AstraZeneca previously announced in November for its vaccine, developed in collaboration with the University of Oxford.
The analysis, published in the journal The Lancet on Tuesday, found that the vaccine's efficacy in trial participants who received two full doses of vaccine was 62.1%, and then efficacy in those who received a half dose followed by a full dose was 90%.
"Overall vaccine efficacy across both groups was 70.4%," the researchers – from the University of Oxford, AstraZeneca and other institutions around the world – wrote in the study.
"Here, we present the first interim safety and efficacy data for a viral vector coronavirus vaccine, ChAdOx1 nCoV-19, evaluated in four trials across three continents, showing significant vaccine efficacy of 70.4% after two doses and protection of 64.1% after at least one standard dose, against symptomatic disease, with no safety concerns," the researchers wrote.
More on the study: The study includes data from trials conducted in the United Kingdom, Brazil and South Africa between April and November. The safety data are based on more than 20,000 participants and the efficacy data are based on more than 10,000 participants.
The study says that across all four studies, "the vaccine had a good safety profile." There were 175 severe adverse events in the trials total: 84 events among those who received the vaccine and 91 in the control group. "Three events were classified as possibly related to a vaccine," according to the study. Those included a case of haemolytic anaemia, transverse myelitis and high fever.
There were four deaths during the course of the trials, but all were unrelated to the vaccine, caused by a road traffic accident, blunt force trauma, homicide and fungal pneumonia.