• Coronavirus EG.5 and BA.2.86, the new Covid variants in the WHO's spotlight

Scientists around the world are conducting experiments and studies to analyze the highly mutated BA.2.86 variant of the virus that causes Covid-19, dubbed Pirola on social media. The first results they are publishing has generated some tranquility.

Two groups – one in China and one in Sweden – have published the results of their studies, which define BA.2.86 as a highly mutated variant, radically different from any other seen so far, but not very transmissible. These are the first results, which still need to be taken with caution, but the elements collected are nevertheless positive.

This new mutation has more than 30 changes in its main protein compared to its closest ancestor, BA.2, and the XBB.1.5 (Kraken) variant that has recently circulated. It was an evolutionary leap on par with the original Omicron variant, BA.1, which first appeared nearly two years ago, when hospitalizations and infections reached their highest levels of the entire pandemic.

In the first series of experiments, using the blood of vaccinated mice and recently infected vaccinated people, researchers in China observed that BA.2.86 is identified very differently by our immune system than previous versions of the virus, so it is able to escape our immunity.

The BA.2.86 variant of Sars-CoV-2 "is antigenically distinct from XBB.1.5," i.e., the Kraken variant, "and can escape neutralizing antibodies." The efficacy of the updated vaccine must be carefully monitored" for this new variant. "However, it is possible that BA.2.86 will not prevail very quickly due to its lower infectivity," summarizes researcher Yunlong Cao of Peking University's Center for Biomedical Innovation, who was at the forefront during the Covid pandemic precisely in the evaluation of new variants. It is currently unknown whether this new variant causes more severe disease than previous variants.

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Internationally, health authorities and the World Health Organization closely monitor this variant due to the high number of mutations it carries, in particular in the Spike protein (which the virus uses to attach to human cells).

Of course, the tests carried out in Yunlong Cao's laboratory suggest that its infectivity "may be much lower than others." The BA.2.86 mutation is about 60% less contagious, which experts say could explain why it has been found in so many different countries, but only at low levels. According to scientists, Pirola, circulates slowly among the population.

In a second series of experiments, researchers at Sweden's Karolinska Institutet compared BA.2.86 with antibodies in the blood of human donors collected at two different times: in 2022, before the XBB variant emerged, and in late August. Antibodies in older samples failed to effectively block BA.2.86, but blood samples taken from donors just a week before the experiment worked better. The new variant seems able to escape the immunity developed with previous infections or with the vaccine, but for those who have recently contracted infections the immune response is not entirely ineffective. "Overall, it does not appear that we are in as extreme a situation as when Omicron emerged," lead researcher Benjamin Murrell wrote in a publication.

Both studies have limitations. The researchers were testing pseudoviruses, which are essentially models of what the BA.2.86 virus looks like, and not the virus itself. The Swedish study used only a small number of blood donor samples. And because these studies used blood donors in China and Sweden, they may not reflect the immunity of people in the rest of Europe or other areas of the world who may have been infected with a different combination of variants and immunized with different vaccines. However, experts seem encouraged by these early discoveries.

Meanwhile, research published on the bioRxiv platform adds new data on the globally dominant EG.5 (Eris) variant. The research, conducted with hamsters, shows that the variant appears to have a greater ability to infect the lungs. This could result in more severe manifestations of Covid-19. However, the data is still to be confirmed.

  • Coronavirus
  • Ómicron variant
  • Covid 19