Results of a clinical trial of the vaccine produced by British-Swedish pharmaceutical company AstraZeneca and Oxford University have become the first to be published in a peer-reviewed scientific journal.
The vaccine AZD1222 was about 70-per-cent effective, scientist Andrew Pollard and his team wrote in the academic journal The Lancet on Tuesday, confirming findings the manufacturers had released in November.
The study showed that the vaccine was generally safe, as only three of the 24,000 respondents developed severe side effects over three and a half months although it was not sure whether the side effects were to do with the vaccine.
The effectiveness of the vaccine depended on whether respondents had received two full doses – as required – or whether they belonged to a group which by accident had only received half a dose at the first inoculation.
Both groups however barely contained persons over the age of 55, therefore it was difficult to make claims about the jab’s effectiveness for elderly people, who are particularly at risk from COVID-19.
The scientists could also not confirm how long the vaccine would guarantee immunity from the virus.
The vaccine is based on a weakened chimpanzee cold virus and contains protein elements of the outer shell of the coronavirus.
The jab is meant to promote the building of antibodies against the virus and the production of T-cells, which are both important for an immune response.
Countries worldwide have ordered billions of doses of the vaccine, which was tested in Britain, Brazil and South Africa.