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The Oxford / AstraZeneca vaccine may have a “substantial effect” on transmission of the coronavirus, and a three-month gap between doses does not reduce protection, according to a report.
Results from Oxford University tests, published in a pre-print report with The Lancet, showed a 67% reduction in COVID-19 swabs among those vaccinated.
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In the report, the university also said that a single standard dose of the Oxford / AstraZeneca vaccine is 76% effective from day 22 to day 90 after injection.
This means that protection is not reduced in the three months between the first and the second dose.
The report supports the government’s strategy that implementing the first doses, with a second dose after three months, is effective in reducing the disease.
After the second dose, the efficacy is 82.4%, if the interval between punctures is three months.
Professor Andrew Pollard, lead investigator of the Oxford Vaccine Trial and co-author of the paper, said: “These new data provide important verification of the interim data that was used by more than 25 regulators, including the MHRA and the EMA, to deliver the vaccine. authorization for emergency use.
“It also supports the policy recommendation made by the Joint Committee on Vaccination and Immunization (JCVI) of a booster interval of 12 weeks, as they seek the optimal approach to implement, and assures us that people are protected for 22 days after a single dose of vaccine “.
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Analysis: This latest research is immensely reassuring
By Thomas Moore, Science Correspondent
The evidence for delaying the second dose of the vaccine has been scant, so new research on the Oxford vaccine is immensely reassuring.
Scientists who developed the vaccine at the Jenner Institute have analyzed more data from the UK clinical trial, including 201 more cases of COVID.
They say it shows that one dose of the vaccine prevented 76% of infections and there was no drop in protection for the next 90 days.
That’s important because government vaccine advisers have recommended that the second dose can be delayed for up to 12 weeks.
The large gap between doses also appears to increase the effectiveness of the vaccine.
If the interval was less than six weeks, the vaccine was 55% effective. But that increases to 82% if the doses were spaced 12 or more weeks apart.
The third significant finding from the study, which was submitted to The Lancet medical journal but has not yet been peer-reviewed, is that the vaccine is likely to reduce transmission of the virus.
PCR tests showed that there was a 67% reduction in positive swabs in those who had been vaccinated. In other words, there were fewer people with asymptomatic infections who could transmit the virus.
Reducing transmission is essential for there to be any chance of herd immunity against the virus that causes COVID.
But while these are very encouraging data for the Oxford vaccine, there is no firm evidence that any of the other vaccines are still as effective with a delayed second dose.
Yet it is the kind of evidence that would have reassured independent scientists when the UK’s medical regulator, the MHRA, announced in December that the second dose of the vaccine would be delayed to speed up the launch.
There have been concerns that it could leave people exposed to the infection.
In normal times, scientists would have waited for copper-bottomed tests from clinical trials before applying for a license.
The pandemic and the rapid spread of the Kent variant meant that the vaccine had to be implemented before the evidence was complete.
And it seems to have been worth it.
