The AstraZeneca COVID-19 vaccine does more than prevent people from becoming seriously ill – it appears to reduce the transmission of the virus and provide strong protection for three months with just a single dose, researchers said on Wednesday in an encouraging campaign. suppression of the outbreak.
Preliminary findings from Oxford University, a co-developer of the vaccine, could justify the British government’s controversial strategy of delaying the second shot by up to 12 weeks, so that more people can be given a first dose quickly. To date, the recommended time between doses has been four weeks.
Research could also bring scientists closer to an answer to one of the big questions about the impetus for vaccination: Will vaccines actually reduce the spread of coronavirus?
It is unclear what implications, if any, the conclusions might have for the other two major vaccines used in the West, Pfizer and Moderna.
In the United States, Dr. Anthony Fauci, the nation’s foremost expert on infectious diseases, rejected the idea of deliberately delaying the second shooting, saying the United States would “go after science” and data from clinical trials. The two doses of Pifzer and Moderna vaccines are expected to be given three to four weeks apart.
However, the research seems to be good news in a desperate effort to stop the spread of the virus and also suggests a way to alleviate vaccine shortages and get photos in more arms faster.
The manufacturers of the three vaccines said their photos have been shown to be between 70% and 95% effective in clinical trials in protecting people from diseases caused by the virus. But it was unclear whether the vaccines could suppress the transmission of the virus – that is, whether someone inoculated could get the virus without getting sick and spreading it to others.
As a result, experts said that even people who have been vaccinated should still wear masks and keep their distance from others.
However, the Oxford study found that the vaccine not only prevents severe disease, but appears to reduce the transmission of the virus by two-thirds. The study has not yet been evaluated by colleagues.
Study volunteers underwent regular nasal swabs. The level of virus-positive swabs – both in those with COVID-19 symptoms and in those who had none – was 67% lower in the vaccinated group.
“This must have a beneficial effect on transmission,” Oxford researcher Sarah Gilbert told a meeting at the New York Academy of Sciences.
The researchers also looked at how likely people who were vaccinated to get an asymptomatic infection were. In a subgroup of volunteers, there were 16 asymptomatic infections among those vaccinated and 31 in an unvaccinated comparison group.
Pfizer and Moderna are also studying the effect of their vaccines on asymptomatic infections.
Only Pfizer and Moderna vaccines are used in the United States. The UK uses both AstraZeneca and Pfizer. AstraZeneca’s has also been licensed by the European Union of 27 nations. Pfizer did not approve of the British government’s decision to extend the time between doses.
Mene Pangalos, executive vice president of biopharmaceutical research and development at AstraZeneca, said no patients had severe COVID-19 or needed hospitalization three weeks after receiving the first dose and that efficacy appears to increase up to 12 weeks. after the initial vaccination.
“Our data suggests you want to be as close to 12 weeks as possible” for the second dose, Pangalos said.
British Health Secretary Matt Hancock said the study “supports the strategy we have taken” to ensure that more people get at least one shot. The UK’s decision has been criticized as risky by other European countries.
Stephen Evans of the London School of Hygiene and Tropical Medicine said the study’s suggestion that a single dose protects people for 12 weeks was “useful, but not definitive.”
He said the authors themselves acknowledged that their research was not designed to investigate the vaccine dosing schedule and that their findings were based on statistical modeling, not on actual patients tracked over time.
“There is certainly not very strong evidence, but there is no indication that this is wrong,” Evans said of Britain’s strategy.
One Oxford researcher, Dr Andrew Pollard, said that scientists also believe that the AstraZeneca vaccine will continue to provide protection against new variants of COVID-19, although it is still awaiting data on this. Rapidly spreading mutant versions have caused alarm around the world.
“If we need to update vaccines, then it’s actually a relatively simple process. It only takes a few months, rather than the huge effort that everyone went through last year to conduct the tests on a very large scale, “Pollard told the BBC.
Meanwhile, a UN-backed program to provide COVID-19 vaccines to the most needy people around the world is preparing for a troubled start. The COVAX facility on Wednesday announced plans for an initial distribution of about 100 million doses by the end of March and more than 200 million by the end of June to dozens of countries.
Almost all the doses expected for the first phase will come from AstraZeneca and its partner, Serum Institute of India. The launch will be conditioned by the fact that the World Health Organization authorizes the shooting of AstraZeneca for emergency use, which is expected to happen this month.
About 190 countries and territories participate in COVAX, which has seen rich nations collect vaccine supplies, sometimes at premium prices.
The total death toll from the pandemic has eclipsed 2.2 million, including about 447,000 in the United States, according to Johns Hopkins University.
New cases a day in the US and the number of Americans in the hospital with COVID-19 have fallen sharply in the last few weeks, but deaths are still close to all-time highs, averaging about 3,100 a day. Deaths often remain behind the infection curve, as it can take several weeks to become ill and die from COVID-19.
As the Super Bowl approaches, Fauci warns people not to invite others to Super Bowl parties, urging spectators to “relax and cool off” to avoid turning Sunday’s big game into an event. super-spreader.
“You don’t want parties with people you haven’t had much contact with,” he told NBC’s “Today.” “You just don’t know if they’re infected.”
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Associated Press reporters Jill Lawless, Maria Cheng, Jamey Keaten and Ricardo Alonso-Zaldivar contributed to the report.
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