Photographer: Dhiraj Singh / Bloomberg
Photographer: Dhiraj Singh / Bloomberg
AstraZeneca Plc’s Covid vaccine showed 82% effectiveness with a three-month difference between two shots, according to a new study that reinforces the UK’s controversial decision to adopt an extended dosing interval.
The vaccine can also significantly reduce the transmission of the virus, according to the analysis of the test data by the Oxford University, which developed the shot with the British pharmacist. Swabs taken from volunteers in the British trial group showed a 67% reduction in transmission after the first dose, the showed the report.
The UK approved giving the first and second two-shot vaccine injection four to 12 weeks apart in an effort to stretch scarce supplies as manufacturing accelerates. AstraZeneca executives had previously said that the larger gap, compared to the three- to four-week period between vaccines recommended for other vaccines, could also increase efficacy.
Covid-19 vaccinations exceed 100 million doses worldwide
The new results are another boost for the vaccination program in the UK, which has surpassed European Union countries and given initial shots to 14% of residents. If the Astra vaccine also reduces transmission, it will speed up the process of achieving herd immunity, when the virus can no longer penetrate a population.
According to new data, the effectiveness of the vaccines increased by 55% with a dosing interval of less than six weeks and up to 82%. The analysis also found that the shot showed 76% protection after the first of the two injections. This level of immunity was achieved from 22 days after the first shot.
The AstraZeneca vaccine had shown an average protection of 70% in previous results of extensive clinical trials. These results came from two subsets, one of which provided 62% efficacy, the other 90%, with different dosage levels in the two groups. When the UK approved the vaccine in December, regulators indicated that they thought the discrepancy was more related to the interval between shots than to the dosage level.
More cases
Initial results were based on 131 cases of symptomatic Covid-19 in the trials, a number that has since grown to 332, allowing for a deeper analysis. The new data is based on information from more than 17,000 participants in trials in the UK, Brazil and South Africa, Oxford said.
The European Union has also approved the vaccine, with France, Germany and some other countries restrict its use to the elderly, citing the lack of data from trials in older age groups.
“These new data provide important verification of the interim data used by more than 25 regulators,” Andrew Pollard, chief investigator at the Oxford trial and co-author of the paper, said in a statement. He also supports the policy recommendation made by the UK vaccine advisory group, he said.
Oxford also plans to publish data on how the vaccine interacts with new ones coronavirus variants in the coming days. The university said it expects the findings to match those of other developers.
Moderna Inc. he said last month that his vaccine would protect against two known variants of coronavirus, but plans to start studies in humans on a booster shot for a South African strain that can cause immunity to decline more quickly. Pfizer Inc. it is also looking to develop a reinforcing feature.
– With the assistance of Stephanie Baker
(Updates with more data from the report from the fourth paragraph)