South Africa on Sunday halted the use of the AstraZeneca-Oxford coronavirus vaccine as vaccines did not protect clinical trial volunteers from mild or moderate disease caused by the more contagious virus variant after evidence emerged .
Was a devastating blow to the findings Country’s efforts to deal with the epidemic.
Scientists in South Africa said Sunday that a similar problem occurred for people infected with older versions of coronaviruses: naturally acquired immunity did not appear to protect them from mild or moderate cases when they were confirmed by the variant, Known as B.1.351.
The developments, which came about a week after a million doses of the AstraZeneca-Oxford vaccine in South Africa, were a major setback for the country, where more than 46,000 people are known to have died from the virus.
The number of cases evaluated as part of the studies outlined by South African scientists on Sunday was small, making it difficult to find out how effective the vaccine variant is.
And because clinical trial participants were evaluated who were relatively young and unlikely to be seriously ill, it was impossible for scientists to determine if the variant Kovid-19, hospital with the variant AstraZeneca-Oxford vaccine Interferes to protect against recruitment or deaths.
The scientists said, however, that they believed vaccines could protect against more severe cases, based on immune responses found in blood samples given by people. If further studies suggest that for this to happen, South African health officials would consider resuming the use of the AstraZeneca-Oxford vaccine, he said.
The new research findings have not been published in a scientific journal. But the discovery of the AstraZeneca-Oxford product showed minimal efficacy in preventing mild and moderate cases of the new version, leading to increasing evidence that B.133 makes current vaccines less effective.
Both Pfizer and Modern have stated that preliminary laboratory studies indicate that their vaccines, while still protective, are less effective than B.1.351. Nowax and Johnson & Johnson have also taken test samples from their clinical trial participants in South Africa, where B.1.351 caused the majority of cases, and both reported lower efficacy than in the United States.
“These results are very much a reality check,” said Shabbir Madhi, a virologist at the University of Witwatersrand who conducted a trial of the AstraZeneca-Oxford vaccine in South Africa.
The stagnation in the country’s rollout of the AstraZeneca-Oxford vaccine means that now the first shipment will be placed in warehouses.
Instead, South African health officials said they would vaccinate health workers in the coming weeks with the Johnson & Johnson Vaccine, which has shown a strong impact in preventing serious cases and hospitalizations due to the new version.
Johnson & Johnson has applied for an Emergency Use Authority in South Africa. But health officials there indicated that some health workers may be given the vaccine as part of ongoing testing before it is authorized.
In the AstraZeneca-Oxford trial in South Africa, approximately 2,000 participants were given two doses of vaccine or combo shots.
There was almost no difference in the number of people in the vaccine and placebo groups who were infected with B.1.351, suggesting that the vaccine did little to protect against the new variant. Nineteen of the 748 people who were vaccinated in the group were infected with the new version, while 20 of the 714 people in the group were given a placebo.
This is equivalent to 10 percent of vaccine efficacy, although scientists did not have sufficient statistical confidence to know whether this figure would be among more people.
The researchers also performed laboratory experiments on blood samples from those who were vaccinated and found a significant decrease in activity levels of vaccine-borne antibodies against type B.1.351 compared to other lineages.
Beyond the disturbing news about the AstraZeneca-Oxford vaccine, Drs. Madhi based on the evidence that previous infections with older versions of coronovirus did not protect people in South Africa from version B.1.351.
To determine who was previously infected with the coronovirus, the researchers tested blood samples from people who were enrolled in a trial of the Novavax vaccine, but who were given placebo shots and not the vaccine themselves.
Researchers compared levels of infection of the new variant to those who had previously shown evidence of having Sevid-19 with levels of infection in those with no difference.
It has been suggested, Drs. Madhi wrote on a slide presented Sunday night that, “past transitions by the ‘original’ variants of SARS-CoV-2 do not protect the light and medium Kovid-19 from the B.1.351 variant.”
He said that it was possible that the B.1.351 variant had the ability to evade the immune response in those who had previously been infected, at least in part due to the fact that South Africa had detected the virus in recent months Why have you faced such a devastating second wave.
Researchers at the University of Oxford acknowledged on Sunday that the vaccine provided “minimal protection” against mild or moderate cases of type B.1.351. They are working to produce a new version of the vaccine that can protect against the most dangerous mutations of the type B1.151, and they have said that it is expected that it will be ready by the fall.
“This study confirms that the epidemic will continue to find ways to spread to populations for coronovirus vaccination,” Andrew Pollard, chief investigator of the Oxford Vaccine Trial, said in a statement. “But, taken with promising results from other studies in South Africa using a similar viral vector, vaccines may continue to reduce the toll on health care systems by preventing critical illness.”
Modern has also started developing a new form of its vaccine that can be used as a booster shot against variants in South Africa.
B.1.351 has become the dominant form of the virus in South Africa and has been found in several dozen countries. a Small number of cases In South Carolina, Maryland and Virginia have been reported.
Scientists believe that B.1.351 may be more adept at dodging protective vaccine-borne antibodies because it has acquired a mutation, Known as E484K, Which makes it harder for antibodies to catch on the virus and prevent it from entering the cells.
Novaxax Asked its vaccine In its South Africa trial, Kovid-19 was just 50 percent effective at stopping it. Johnson and johnson informed of Its single-shot vaccine was 57 percent effective at preventing moderate-level severe Kovid-19 in South Africa, although it still offered complete protection from hospitalization and death after four weeks.
Another rapidly spreading version of the virus, known as B.1.1.7 and first identified in the UK, does not interfere with the vaccine. All major vaccines, and most recently AstraZeneca’s product, offer the same level of protection against B.1.7 as compared to the virus’s earlier.
AstraZeneca’s vaccine has been authorized by about 50 countries, including Britain, which have found dozens of cases of the first-seen variant in South Africa. Although many countries greatly reduce the virus, making it difficult to know if the B.1.351 variant has caught up there, it does not yet appear effective in any country outside South Africa.
In the United States, regulators await data from a large, late-stage clinical trial of AstraZeneca-Oxford, which is expected to report results in March.