AstraZeneca’s COVID-19 vaccine is more effective if you wait three months for the second dose than with the six weeks they are spaced today, according to a study published in The Lancet magazine. This find would be in line with UK vaccination policy and the latest WHO recommendations for the Anglo-Swedish company vaccine.
The study found evidence that the effectiveness of the vaccine in those who had an interval of twelve weeks or more between doses reached 81.3% compared to 55.1% in those with an interval of less than six weeks. Additionally, a single dose of the AstraZeneca vaccine had a 76% effectiveness in the first 90 days, although “it is not clear how long this single because the follow-up is limited to periods of time (…) and, for this reason, a second dose is recommended ”.
24,422 people were recruited between April 23 and December 6, 2020 for a total of four studies. Of the total, 17,178 were used for the analysis of the efficacy of the vaccine (8,597 received it and 8,581 were part of the control group), while 8,948 belonged to the British trials, 6,753 to the trials in Brazil, and 1,477 to the trials in South Africa.
In line with the British strategy
The results would support the UK’s “first dose first” strategy, with which 22% of the population has already received at least one of the two doses. In the country governed by Boris Johnson, it was decided to vaccinate the largest number of people with the first dose and space up to twelve weeks the administration of the second.
The British decision divided the scientific community and the government argued that it was a matter of necessity given the country’s health collapse situation. A few days ago, the World Health Organization extended the gap between the two doses of the Oxford-AstraZeneca vaccine to 8-12 weeks, a recommendation that appears to be supported by this recent research.