Three years after the appearance of the coronavirus, a new variant, XBB.5.1, has quickly become the dominant strain in parts of the United States as a result of a powerful mix of mutations that make it easy to spread widely, even among those Those who have previously been infected or who have been vaccinated, according to a report in the "Washington Post".

Cases of "XBB 5.1", which the World Health Organization has classified as the "most transmissible" descendant to date of the "omicron" variant, have risen from barely 2% of cases in the United States at the beginning of last December to more than 27% in the first week of January, according to estimates by the Centers for Disease Control and Prevention.

Did the "XBB 5.1" strain evolve as a result of vaccination?

While there is no evidence yet that XBB 5.1 is more virulent than its predecessors, the recent misinformation swirl linking vaccination to the emergence of new variants has shed light on this latest strain, and some health experts fear it could spread further.

"XBB 5.1 didn't evolve because people were vaccinated, let's be honest, but the way it evolved is that people were infected with multiple viruses at the same time," said von Cooper, a professor of evolutionary biology at the University of Pittsburgh.

Virologists who have studied XBB 5.1 say it not only appears to be better at evading antibodies than its immune-evading progenitors, but it is better at attaching to a cell and reproducing.

This means that it can become the dominant strain in society, but it does not necessarily exacerbate the symptoms of Covid-19 disease.

US health officials are urging a booster dose of a novel coronavirus vaccine designed for sub-Omicron variants to protect against an expected winter surge.

Jesse Blum, an evolutionary biologist at the Fred Hutchinson Cancer Center in Seattle, said that many studies have tried to examine whether Covid-19 variants spread faster in locations with higher vaccination rates, but this hypothesis has not been proven by any evidence to support it.

Bloom asserts that "XPP 5.1" is kind of the latest variant, in what appears to be an ongoing process of virus evolution, and that this same virus could see other mutations.

Clarifications of the US Food and Drug Administration

In a statement issued by the US Food and Drug Administration last Friday, it said that it does not expect that Evusheld will neutralize XBB 5.1, meaning that Evusheld may not provide protection against the development of COVID-19 in individuals who have COVID-19. They received this drug and were subsequently exposed to XBB 5.1.

"However, we are awaiting additional data to verify that EvoShield is not active against XBB 5.1," the FDA added. "We will provide further updates as soon as new information becomes available."

EvoShield is a treatment based on injections of "Monoclonal Antibody", which is taken proactively to help enhance the immune response in groups at risk, and helps protect them for up to 6 months.

EvoShield is given in two doses by injection, but it does not replace vaccination, as experts confirm, as vaccines are still believed to be the best to reduce the risk of hospitalization due to Covid-19.

EvoShield is also given to people who did not receive the vaccine due to potential health risks according to their medical records, such as allergic reactions.

Spread in Germany

For his part, epidemiologist Hayo Zip, from the German Leibniz Institute for Disease Prevention and Epidemiology Research in Bremen, said, "It can be said, with some predictive certainty, that this variant will become dominant in our country as well."

He added that the "XBB 5.1" mutant is spreading in light of the weak immunity of people who have been vaccinated or infected some time ago, noting that the mutant spread first in the United States, then it will spread in Germany.

However, Tsep stresses that the number of detected cases of the "XBB 5.1" variant in Germany is still very low at the present time, and he said, "There is no need yet to think about new measures."