Photographer: Dhiraj Singh / Bloomberg
Photographer: Dhiraj Singh / Bloomberg
AstraZeneca Plc’s Covid vaccine has shown 82% efficacy with a three-month gap between two shots, according to a new study that strengthens the UK’s controversial decision to adopt an extended dosing interval.
The vaccination can also significantly reduce the transmission of the virus, according to the analysis of the experimental data by the University of Oxford, which developed the survey with the British drug manufacturer. Swabs taken from volunteers in the British arm of the trial showed a 67% decrease in transmission after the first dose, the report shown.
The UK has approved the first and second injections of two-shot vaccines at four- to 12-week intervals in an effort to expand scarce supplies while increasing production. Managers of AstraZeneca have previously said that the longer gap compared to the period of three to four weeks between shots recommended for other vaccines could also increase efficacy.
CovidVaccinations exceed 100 million doses worldwide
The new results are a further boost to the vaccination program in the UK, which raced ahead of countries in the European Union and initially shot 14% of the population. If the Astra vaccine also reduces transmission, it will speed up the process of establishing herd immunity when the virus can no longer invade a population.
According to new data, the efficacy of the vaccine has increased from 55% with a dose interval of less than six weeks to 82%. The analysis also found that the shot shows 76% protection after the first of two injections. The level of immunity was reached from 22 days after the first shot.
The AstraZeneca vaccine has shown an average of 70% protection in previous results of broad clinical trials. The results come from two subsections, one of which yielded 62% efficacy, and the other 90%, with different dosage levels in the two groups. When the UK approved the vaccine in December, regulators indicated they thought the discrepancy was more likely linked to the interval between shots than the dosage level.
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The initial results were based on 131 cases of symptomatic Covid-19 in the trials, a number that has since grown to 332, allowing for more in-depth analysis. The new data is based on information from more than 17,000 test takers in the UK, Brazil and South Africa, Oxford said.
The European Union also approved the vaccine, with France, Germany and some other countries have restricted its use in the elderly, citing a lack of trial data in older age groups.
“This new data provides an important verification of the interim data used by more than 25 regulators,” said Andrew Pollard, lead investigator at the Oxford trial and co-author of the article, in a statement. It also supports the policy recommendation made by the British Vaccine Advisory Panel, he said.
Oxford also plans to publish data on how the vaccine interacts with new variants of the coronavirus in the coming days. The university said it expects the findings to be in line with those of other developers.
Moderna Inc. said last month that his vaccine would be protected against two known coronavirus variants, but he plans to start human studies with a booster shot for a strain from South Africa that could reduce immunity faster. Pfizer Inc. also wants to develop a booster shot.
– With help by Stephanie Baker
(Updates with more information from the report begin in the fourth paragraph)