Longer Oxford-AstraZeneca vaccine interval improves efficacy, report says

pharmafile | February 3, 2021 | News story | Research and Development AstraZeneca, COVID-19 

A longer interval between doses of the Oxford University-AstraZeneca vaccine could substantially improve efficacy, according to a report published in the Lancet.

The study, conducted by Oxford University, details an increased efficacy of 82.4% following a second dose administered three months after the first, in contrast to an efficacy of just 54.9% with an interval of six weeks or less.

The report also shows a single dose efficacy of 76%, with this level of protection not appearing to fall between 22 and 90 days.

These data would support the decision by health officials in the UK to delay the delivery of a second dose from three to twelve weeks, although it is worth noting that the study does not contain data on the Pfizer-BioNTech vaccine.

The report also found that a single dose of the vaccine could also slice transmission rates by 67%, based on swabs from volunteers in the trial. This is based on a study of 332 cases of primary symptomatic COVID-19.

Professor Andrew Pollard, Chief Investigator of the Oxford vaccine trial, and co-author, told the Oxford University website: “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 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.”

Jack Goddard

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