The Oxford University/Astrazeneca Covid-19 vaccine could cut the transmission of infections by two-thirds and a three-month delay between doses does not reduce efficacy, a new report has found.
A pre-print paper published by Oxford and the Lancet found there was a 67 per cent reduction in positive swabs among those vaccinated.
The research also found that the jab was 76 per cent effective from 22 days until 90 days after a single standard dose.
This means protection from the virus does not diminish in the three-month period between the first and second dose.
The findings support the government’s to extend the gap between first and second jabs to 12 weeks in an effort to roll out the vaccine to as many Brits as possible as quickly as possible.
However, it did not address concerns about the efficacy of the vaccine among older people, who have been given highest priority.
Andrew Pollard, chief investigator of the Oxford vaccine trial, said the data showed the 12-week interval between doses was “the optimal approach to roll out, and reassures us that people are protected from 22 days after a single dose”.
The results of the tests showed that immune responses were boosted with a longer interval before the second dose among participants aged between 18 and 55.
The paper said efficacy was 82.4 per cent when the second dose was administered after three months, compared to 54.9 per cent when the booster was given under six weeks after the first dose.
Health secretary Matt Hancock hailed a “really encouraging study”, adding: “Vaccines are the way out of this pandemic and we are making fantastic progress vaccinating the most vulnerable.”