Oxford COVID-19 vaccine efficacy would look higher if trial tested for severe virus

LONDON (Reuters) - The experimental COVID-19 vaccine developed by AstraZeneca and Oxford University would have a higher efficacy rate if trials were only measuring whether the shot prevents hospitalisation and severe disease, Oxford's vaccine chief said on Monday.

Speaking in a briefing, Andrew Pollard, director of the Oxford Vaccine Group, said it is hard to explain the different efficacy rates between the AstraZeneca/Oxford shot and the other vaccines developed by Pfizer and BioNTech and one by Moderna.

Pfizer-BioNTech and Moderna late-stage studies showed efficacy of more than 90%, while the British shot was on average 70% effective after testing its efficacy for all levels of the disease from severe to mild.

One reason may be that the companies are measuring for different things, Pollard said.

There may also be real differences between all the vaccines, he said.

(Reporting by Kate Kelland, Kate Holton and Guy Faulconbridge; Writing by Josephine Mason; Editing by Toby Chopra)