A three-month interval between doses of the AstraZeneca-Oxford COVID-19 vaccine shows better results than a six-week gap currently recommended, according to a study published in the respected UK-based journal The Lancet.
The first dose can offer up to 76 per cent protection in the months between the two jabs, the results of the analysis from a Phase 3 randomised controlled trial suggest. Given the high rate of protection, the interval between doses can be safely extended, it said, adding this will allow more people to be immunised – as doses are currently in short supply in many places.
“Vaccine supply is likely to be limited, at least in the short term, and so policy-makers must decide how best to deliver doses to achieve the greatest public health benefit,” said the lead author of the study, Professor Andrew Pollard, the University of Oxford.
“In the long term, a second dose should ensure long-lived immunity, and so we encourage everyone who has had their first vaccine to ensure they receive both doses,” he added.
The study sought to understand the effects of different intervals between jabs on protection after the second dose, and the risk of infection between doses.
The researchers combined data from clinical trials in the UK, Brazil, and South Africa, which together included a total of 17,178 adult participants.
“This latest analysis confirms our previous findings of the higher efficacy of a low- then standard-dose regimen,” said study co-author Merryn Voyse, also from Oxford.
“However, with additional data available, we have found that the enhanced efficacy and immunity may be partly driven by the longer interval between doses that was common in this trial group.”