Paramedics with a Covid-19 patient in Johannesburg on Monday.
Photo: michele spatari/Agence France-Presse/Getty ImagesJOHANNESBURG—A new variant of the coronavirus that is surging across South Africa may make the existing Covid-19 vaccines less effective, but is unlikely to be totally resistant to the shots, according to leading researchers who have studied the mutations and the vaccines.
The variant, which has already shown up in patients in Europe and other African countries, has quickly become the predominant one in South Africa, exacerbating a second wave of infections that is overwhelming hospitals and has driven daily deaths to record highs.
South African researchers are racing to determine whether it makes patients more seriously ill than other variants of the virus. They are also testing how it responds to antibodies from people who have recovered from Covid-19 and those who have received coronavirus vaccines.
Their official conclusions are eagerly awaited by researchers around the globe, since one of the variant’s mutations has in earlier laboratory experiments shown increased resistance to some of the antibodies the body uses to fight off Covid-19. U.K. Health Secretary Matt Hancock said earlier this week that he was “incredibly worried about the South African variant.”
But scientists who worked on the antibody experiments and the lead investigators of several vaccine trials being conducted in South Africa say that—based on their understanding of the virus and the immune response triggered by the shots—the immunizations should still work against the new variant, although perhaps not as effectively.
“The immune response is a complex part of our body and we know that immune response isn’t just about neutralizing antibodies,” said Glenda Gray, the head of the South African Medical Research Council and one of the lead investigators of the Johnson & Johnson vaccine trial in the country.
Passengers waited to be tested outside an airport in Johannesburg on Tuesday.
Photo: Guillem Sartorio/Bloomberg NewsCovid-19 vaccines are designed to trigger an immune response that includes antibodies that shouldn’t be affected by the new mutations as well as blood cells, known as T-cells, which attack the virus more broadly.
The two vaccines already approved in the U.S.—one developed by BioNTech SE and Pfizer Inc. and the other by Moderna Inc. —have shown to protect more than 90% of the people who get them from Covid-19 symptoms. The immunization developed by the University of Oxford and AstraZeneca PLC, which has been approved in the U.K. and India, was 62% effective in preventing symptomatic Covid-19 in trials in the U.K. and Brazil.
“There might be some attenuation on the effectiveness of the vaccines,” said Shabir Madhi, the lead investigator of the South African trials of the Oxford/AstraZeneca vaccine and the one being developed by Novavax Inc.
A spokeswoman for BioNTech said the company expects to release results from its own tests on the South African variant later this week, but generally isn’t concerned about the new mutations. A spokesman for the University of Oxford said they were still working on tests on the new variant. Moderna has said it is confident its vaccine will be effective at inducing neutralizing antibodies against new variants of the virus.
New daily cases recorded in South Africa, a country of 60 million people, reached a new record of 21,832 on Wednesday. Nearly a third of all Covid-19 tests are coming back positive, suggesting that the real number of infections is much higher.
A reduction in a vaccine’s efficacy could mean that a higher percentage of recipients are still susceptible to getting Covid-19 or that they may still get a mild form of the disease. It could also mean that a larger proportion of people need to get vaccinated to produce herd immunity and end the pandemic.
Dr. Madhi and Dr. Gray said results from the South African trials on the Oxford/AstraZeneca, Novavax and Johnson & Johnson vaccines should be available in the coming weeks. Because participants will have mostly come into contact with the new variant, the results will show how vaccinated people respond to the mutations, rather than just conducting tests with virus cells and antibodies produced in a lab.
Scientists haven't determined how much less effective the vaccines could be on the new variant, if at all, but the trials could help answer that.
“It’s a very unique opportunity,” said Dr. Gray.
Concern over the South African variant’s impact on the efficacy of vaccines has centered on a mutation dubbed E484K. Researchers believe that mutation has changed the shape of the virus’s spike protein, which it uses to attach to and infect human cells, in a way that makes it harder for some antibodies to get a good grip and neutralize the virus.
It is normal for viruses to mutate and most mutations observed so far in the coronavirus have made little difference to how it functions. The South African variant, along with a separate one found in the U.K., have worried scientists because of their unusually large number of mutations, especially in the spike protein.
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In addition to the E484K mutation, the scientists who sequenced the South African variant’s genome also found a mutation—known as N501—that researchers in the U.K. have said may be responsible for the much faster spread of the virus there. Like in the U.K., the new South African variant has quickly crowded out other versions of the virus in the country, also suggesting that it is more transmissible. Scientists don’t believe that the N501 mutation will affect the efficacy of vaccines.
In the past two weeks, laboratories in Finland, the U.K., Australia, Switzerland, Japan and South Korea have found the South African variant in coronavirus tests conducted there. Researchers in neighboring Zambia say the South African variant now also appears to be the dominant virus there.
One reason why the new variant emerged in South Africa may be that the country already suffered through a bad first wave of infections. In some impoverished townships, more than 40% of people visiting clinics for other conditions have been shown to have Covid-19 antibodies in their blood. Those antibodies protect them from older variants of the virus, but new variants could circumvent such immunity.
Michel Nussenzweig, who heads the Laboratory of Molecular Immunology at the Rockefeller University in New York, leads a team of researchers who implanted the spike protein from the coronavirus into a much-faster-mutating virus. That gave them a kind of time-lapse view of how the virus reacts when it comes under pressure from antibodies cloned from the blood of people who have recovered from Covid-19.
One of the mutations that appeared during these experiments was E484K, the one that has now shown up in the South African variant. The Rockefeller team found that the E484K mutation knocked out one important class of antibodies, out of a total of four classes.
But Dr. Nussenzweig said that other elements of a person’s immune response—whether triggered by a vaccine or an earlier infection—could still protect against Covid-19.
Scientists also said that if the South African variant does indeed have a significant effect on vaccine efficacy, immunizations using messenger RNA, like the BioNTech/Pfizer and Moderna ones, or those relying on other viruses as a vector, such as the Oxford/AstraZeneca vaccine, could quickly be adapted to produce more effective antibodies.
Because such changes would be relatively minor, regulators may agree to approve adapted vaccines without the full spate of human trials that was necessary for the first round of Covid-19 immunizations. “The flu vaccine (which needs to be adapted every year) is a good example,” said Dr. Madhi.
Write to Gabriele Steinhauser at gabriele.steinhauser@wsj.com
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January 07, 2021 at 03:11AM
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