New data on the Oxford/AstraZeneca vaccine has suggested that it may have a substantial impact on transmission of COVID-19.
Analyses of PCR positive swabs from the UK population suggests that vaccination may have a substantial effect on transmission of the virus with a 67% reduction in positive swabs among those vaccinated. Data has also demonstrated that the COVID-19 vaccine shows sustained protection of 76% during the three-month interval until the second dose.
The findings have been published in Preprints with The Lancet.
The University of Oxford researchers have revealed that the vaccine efficacy is higher at longer prime-boost intervals, and that a single dose of the vaccine is 76% effective from 22- to up to 90-days post vaccination. They report that the effect of dosing interval on efficacy is pronounced, with vaccine efficacy rising from 54.9% with an interval of less than six weeks to 82.4% when spaced 12 or more weeks apart.
They also detail that a single standard dose of the vaccine is 76% effective at protecting from primary symptomatic COVID-19 for the first 90 days post vaccination, once the immune system has built this protection 22 days after the vaccination, with the protection showing little evidence of waning in this period.
Professor Andrew Pollard, Chief Investigator of the Oxford Vaccine Trial, and co-author, said: “These new data provide an important verification of the interim data that was used by more than 25 regulators including the MHRA and EMA to grant the vaccine emergency use authorisation.
“It also supports the policy recommendation made by the Joint Committee on Vaccination and Immunisation (JCVI) for a 12-week prime-boost interval, as they look for the optimal approach to roll out, and reassures us that people are protected from 22 days after a single dose of the vaccine.”