Friday, August 12, 2022

We may soon know if vaccines work against a frightening new variant of the coronavirus

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When first detected, the South African variant appeared worrying due to the large number of mutations it had acquired, 23 in all, and the number of these in the critical spike protein, which the virus uses to attach itself to human cells. This strongly suggested that the virus was evolving to avoid antibodies.

Since then, researchers have gathered more alarming clues about 501Y.V2, including from a study that showed that antibodies in the blood serum of around 50 previously infected people were often unable to block the new variant.

“When you test the blood of people from the first wave [we find] in almost half of the cases there is no recognition of the new variant, ”said Penny Moore, researcher at the University of the Witwatersrand in Johannesburg, on the same broadcast.

It’s worrying, but vaccinations can elicit broader and more potent immunity than a transient infection, so it’s impossible to say they still won’t work. And Moore said the blood of some patients, especially those who had become very ill, was still able to neutralize the variant, at least in lab tests. “It’s important when you think about the vaccine, some vaccines cause a very high level of antibodies and some don’t,” she said.

A technician at Rocky Mountain Regional VA Medical Center in Aurora, Colo., Prepares a dose of the Johnson & Johnson covid-19 vaccine for a clinical trial on December 15, 2020.

MICHAEL CIAGLO / GETTY IMAGES

Another signal in favor of vaccines is that, so far, there is no clear evidence that the new strain is more likely to re-infect people who have previously had covid-19. If natural immunity in fact holds, immunity gained from a vaccine probably would too. “Are we seeing a systematic increase in re-infections? The data doesn’t allow us to tell, ”says Karim. Reinfection could still be avoided, he says, because the body “has two immune mechanisms, the B cells which make antibodies and the T cells which swallow things up and kill them.”

The researchers say lab tests alone cannot prove whether the vaccines will work against the new variants, and why they hope the results of ongoing vaccine trials in South Africa, the UK and elsewhere may soon give better answers. “We are expecting a response very soon,” says Karim. “But we want to see the real data, and it’s not yet available.”

Convergent evolution

Scientists are studying two major possibilities where these variants come from. One hypothesis is that the virus evolves in immunocompromised people, where it can persist for months while learning to bypass the immune system. Another idea is that variations are appearing in cities like London, which suffered big waves of infection in early 2020. Millions have been infected, but if their antibodies were to drop during the year, then their bodies could. select virus variants that are able to resist what remains of their immune response.

Some scientists now believe that evolved variants are probably appearing everywhere, not just in Britain and South Africa, but just haven’t been detected yet. “We anticipate that as people increase genomic surveillance, multiple variants will be discovered, especially in places that have had a lot of cases for a long time,” says Tulio de Oliveira, who studies viral genomes at the University of Washington. “Unless we can cut transmission to near zero, the virus will continue to outsmart us.”

Scientists say they’re pretty sure the variants in South Africa and the UK spread faster, causing around 50% more consecutive infections than the strain of Chinese origin. Part of the evidence is how quickly the UK variant, called B.1.1.7, took root elsewhere, outperforming older versions. This already represents almost half of the cases in Israel, which is facing a peak in infections despite a major vaccination campaign. The 501Y.V2 variant, meanwhile, has already been seen in at least 10 countries.



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