AstraZeneca’s COVID-19 vaccine does not prevent people from getting seriously ill – it appears to reduce virus transmission and provide robust protection for three months with just one dose, researchers said Wednesday, an encouraging shift in the outbreak’s suppression campaign. .
Initial results from the University of Oxford, a co-developer of the vaccine, could demonstrate the British government’s controversial strategy of delaying a second shot by up to 12 weeks so more people can be given a first dose quickly. To date, the recommended time between doses has been four weeks.
The research could also bring scientists closer to the answer to one of the big questions about the vaccination campaign: Will vaccines really curb the spread of the Coronavirus?
It is not clear what effects the results, if any, would have on the other two major vaccines used in the West, Pfizer and Moderna.
In the United States, Dr. Anthony Fauci, the nation’s chief infectious disease expert, rejected the idea of deliberately delaying second doses, saying the US would “rely on science” and data from clinical trials. Two doses of the Pifzer and Moderna vaccine should be given three and four weeks apart.
However, the research appears to be good news in desperate efforts to stop the spread of the virus and also suggests a way to mitigate the vaccine shortage and get more vaccines more quickly.
The three vaccine makers said their vaccines have proven effective anywhere from 70% to 95% in clinical trials in protecting people from disease caused by the virus. But it was unclear whether vaccines could also prevent transmission of the virus – that is, whether the person who was vaccinated could still catch the virus without getting sick and spread it to others.
As a result, experts say that even people who have been vaccinated should continue to wear masks and distance themselves from others.
However, the Oxford study found that the vaccine not only prevented severe disease, it appeared to limit virus transmission by two-thirds. The study has not yet been peer-reviewed.
Study volunteers underwent regular nose swabs. The level of positive swabs of the virus – from both those who had symptoms of COVID-19 and those who had no symptoms – was 67% lower in the vaccinated group.
“This should have a really beneficial effect on transmission,” said Sarah Gilbert, senior researcher at Oxford, at a meeting of the New York Academy of Sciences.
The researchers also looked at the likelihood that people who were vaccinated would develop a symptom-free infection. In one subgroup of volunteers, there were 16 asymptomatic infections among those vaccinated and 31 in the unvaccinated control 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. Britain uses both AstraZeneca and Pfizer. AstraZeneca is also licensed by 27 countries in the European Union. Pfizer did not support the UK government’s decision to extend the time between doses.
No patient had been exposed to severe COVID-19 or required hospitalization three weeks after receiving their first dose, said Maine Pangalos, executive vice president of biopharmaceutical research and development at AstraZeneca, and this efficacy appears to have increased up to 12 weeks after the initial shot.
“Our data indicate you want to approach 12 weeks as possible” for the second dose, Pangalos said.
British Health Secretary Matt Hancock said the study “supports the strategy we took” to make sure more people get at least one injection. Other European countries criticized Britain’s decision, describing it as dangerous.
Stephen Evans of the London School of Hygiene and Tropical Medicine said the study’s suggestion that a single dose protected people for 12 weeks was “beneficial but not definitive”.
He said the authors themselves acknowledged that their research was not designed to investigate a vaccine dosing schedule and that their conclusions are based on statistical modeling, not on actual patients who were tracked over time.
Evans said of Britain’s strategy: “It is certainly not a very strong evidence, but there is also nothing to indicate that this is the wrong thing to do.”
One Oxford researcher, Dr Andrew Pollard, said the scientists also believe the AstraZeneca vaccine will continue to provide protection against new variants of COVID-19, although they are still awaiting data on that. The fast-spreading mutant releases have caused concern worldwide.
“If we need to update vaccines, it’s actually a relatively straightforward process. It takes only a few months, rather than the huge effort that everyone put in last year to do very large-scale trials,” Pollard told the BBC.
Meanwhile, a UN-backed program is preparing to provide COVID-19 vaccines to the most needy people around the world after a tumultuous start. On Wednesday, the COVAX facility announced plans for an initial distribution of nearly 100 million doses by the end of March and more than 200 million more by the end of June to dozens of countries.
Almost all of the expected doses for Phase 1 are due to come from AstraZeneca and its partner, Serum Institute, India. The launch will hinge on the World Health Organization allowing the AstraZeneca shot to be used for emergency use, which is expected to happen this month.
About 190 countries and territories participate in COVAX, which has seen rich countries pool their vaccine supplies, sometimes at high prices.
The number of deaths from the epidemic worldwide has exceeded 2.2 million, including about 447,000 in the United States, according to data from Johns Hopkins University.
The number of daily new cases in the United States and the number of Americans hospitalized with COVID-19 have fallen sharply in the past few weeks, but deaths are still nearing their all-time highs, with an average of around 3,100 a day. Fatalities often lag behind the infection curve, because it can take weeks for you to get sick and die from COVID-19.
As the Super Bowl approaches, Fauci warns people against inviting others to Super Bowl parties, urging viewers to “just chill and chill” to avoid turning Sunday’s big game into a great event.
“You don’t want parties with people you haven’t been in much contact with,” he said on NBC’s “Today” program. “You just don’t know if they are infected.”
Associated Press reporters Jill Lawless, Maria Cheng, Jamie Kitten and Ricardo Alonso Zaldivar contributed to this report.
Follow all of the AP’s coverage of the epidemic at https://apnews.com/hub/coronavirus-pandemic, https://apnews.com/hub/coronavirus-vaccine and https://apnews.com/UnderstandingtheOutbreak