AstraZeneca's COVID-19 vaccine is safe and effective, new data from late-stage trials shows.
Overall, the vaccine protected against symptomatic disease in 70% of cases, according to a team led by researchers from Oxford University in England. Among study volunteers who got a half dose and then a full dose, the rate was 90%, while the rate was 62% in those given two full doses.
"Our findings indicate that our vaccine's efficacy exceeds the thresholds set by health authorities and may have a potential public health impact," said Oxford's Andrew Pollard, the lead author on the study.
The interim findings are from phase 3 trials in the United Kingdom and Brazil that included more than 11,600 participants. Most of them (82%) were between the ages of 18 and 55, because older people were recruited later and will be studied in future analyses of the data.
Safety data from nearly 24,000 people in four trials in the United Kingdom, Brazil and South Africa found that, over a median of 3.4 months, only three participants had serious side effects possibly related to the vaccine. All recovered or are recovering and remain in the trial, according to the findings published online Dec. 8 in The Lancet.
"The results presented in this report provide the key findings from our first interim analysis," study author Merryn Voysey, also from the University of Oxford, said in a journal news release. "In future analyses, with more data included as it becomes available, we will investigate differences in key subgroups such as older adults, various ethnicities, doses, timing of booster vaccines, and we will determine which immune responses equate to protection from infection or disease."