That's why the South African variant of the coronavirus worries more than the others

That's why the South African variant of the coronavirus worries more than the others

Reduces the effectiveness of vaccines, cancels the activity of some monoclonal antibodies and may potentially be able to re-infect. Here are the main problems of the South African variant

(image: Pixabay) The undisputed protagonists of this phase of the pandemic are certainly the variants of the coronavirus. And what worries the scientific community the most are the so-called English, South African and Brazilian, now widespread in various areas of our country. To monitor them is the Higher Institute of Health, according to which the vaccines available so far would be fully effective against the English variant, but less so for the Brazilian and South African ones, while as regards the drugs in use and in experimentation some monoclonal antibodies could lose efficacy. . Experts from Columbia University are now shedding light on the issue who, in a new study published in Nature, suggest that the coronavirus is evolving in such a way as to escape therapies and vaccines that target its spike protein, which is the key to access. which allows the virus to enter human cells. What is most worrying, however, is the South African variant. Here's why.

Based on laboratory tests, in which Sars-Cov-2 pseudoviruses were recreated with the eight mutations found in the English variant and the nine mutations in the South African one, the researchers observed that the current vaccines and some antibodies monoclonals may be less effective in neutralizing the English variant (B.1.1.7), but especially the South African one (B.1.351). In particular, the results showed that the antibodies in the blood samples of people who had received the Moderna or Pfizer vaccine were less effective in neutralizing the two variants: against the English one the neutralization was reduced by about 2 times, but against that of South Africa, the neutralization has dropped from 6.5 to 8.5 times.

"The loss of about twice the neutralizing activity against the English variant is unlikely to have a negative impact and we see this in the Novavax results, where the vaccine was found to be 85.6% effective ", comments research author David Ho, referring to the first results reported by the pharmaceutical company, which show that Novavax was found to be approximately 90% effective in the study carried out in the United Kingdom, while only 49.4% in the study conducted in South Africa, where the prevalence of cases is caused by variant B.1.351. “The decline in neutralizing activity against the South African variant is appreciable and we are now seeing, based on the Novavax results, that this is causing a reduction in protective efficacy,” adds Ho.

In the study, moreover , the researchers found that some monoclonal antibodies used today to treat Covid patients may not work against the South African variant. Of the 18 different antibodies examined, most had a still powerful neutralized activity against the English variant, while in 4 antibodies their activity was completely canceled by the South African one. "Decisions on the use of these treatments will strongly depend on the local prevalence of the variants", comments the author.

And again: based on the plasma results of previously infected patients (with the original strain), the South African variant may have the potential to re-infect. From the new analyzes, in fact, the serum of most of these patients showed a neutralizing activity of 11 times lower against the South African variant, and 4 times lower against the English one. "The concern here is that re-infection may be more likely when confronted with these variants, particularly that of South Africa," Ho points out.

Although the survey did not also consider the Brazilian variant (B.1.1.28), the researchers point out that the mutations on the spike protein are very similar to those found in the South African and are therefore likely to behave similarly. "We must prevent the virus from replicating and this means accelerating the vaccination campaign and respecting mitigation measures such as masks and physical distancing," comments the author. "Stopping the spread of the virus will stop the development of further mutations."

To confirm these results there is also a study recently published in Nature Medicine and carried out by Washington University in St. Louis. Always focusing on the English, South African and Brazilian variants, in this case, the researchers found that up to 10 times higher amounts of antibodies could be needed to neutralize the latter two variants (probably due to the E484K mutation, absent in the English one). . Otherwise, the study authors explain, the anti-Covid drugs and vaccines developed so far could become less effective as new variants become dominant.

"There is a great variability in the amount of antibodies a person produces in response to vaccine or natural infection, ”explains lead author Michael S. Diamond. "Some people produce very high levels and are probably still protected by the new variants." But others, especially the elderly and immuno-compromised, may not produce as many. “If the level of antibodies needed for protection increases tenfold, as our data indicate, it may not be enough. The concern is that the people most in need of protection are the ones least likely to have it ”.

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