Fall’s COVID-19 shot may be different in one important way

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This fall, millions of Americans may be preparing for a different kind of COVID vaccine: their first dose that doesn’t contain the complications that started the pandemic three and a half years ago. Unlike the current, bivalent vaccine, which protects against two types at the same time, the next one can, like the first type of shot, have only one thing – the protein spike of XBB.1 line of the Omicron brand, the whole world. modern major clade.

That plan has not been implemented. The FDA is expected to convene a panel of experts, so it is expected to make a final call on autumn foods next month. But several experts told me they expect the agency to follow through the latest recommendations of the World Health Organization’s advisory group and it looks for subsequent vaccinations only for groups that are running.

Change of method – from two types to one, from original SARS-CoV-2 plus Omicron to XPB.1 only– may be important but smart, experts told me, reflecting the world’s latest understanding of the evolution of the virus and how the immune system works. Melanie Ott, director of the Gladstone Institute of Virology, in San Francisco, said: “It sounds good. XBB.1 is the main group of coronaviruses circulating today; Neither the original version nor the BA.5, the two flavors of the coronavirus in the bivalent shot, are any better. And a stable XBB.1 vaccine could give people around the world a chance to boost immunity.

At the same time, the COVID vaccine is still in the form of beta testing. In the last three combined years, the virus has caused countless iterations, many of which have fared better than us; We humans, right now, are on our third attempt to develop a vaccine that can adapt to the evolution of pathogens. And we’re still learning more about the ability of the coronavirus to evolve and change, says Rafi Ahmed, an immunologist at Emory University. By now, it is already known that vaccination is important in preventing severe disease and death, and that further increases are needed to increase the number of shots. But as the virus changes its evolutionary path, our vaccine approach must follow—and experts are still wondering how to respond to those changes when deciding to get the shot each year.

In spring and summer of 2022, the last in the US he was thinking for the new vaccine method, Omicron was still new, and the evolution of the coronavirus seemed to be going well. Viruses spent more than two years throwing Greek letters in error with no known sequence. Instead of multiplying genetic changes in a single line – a mutation, almost similar to what the flu does – the coronavirus produced many similar strains that raced to control. Delta was not a direct descendant of Alpha; Omicron was not an offshoot of Delta; no one could say for sure what would happen next, or when. “We don’t understand what happened,” said Kanta Subbarao, the head of a WHO advisory group meeting to make recommendations on a COVID vaccine.

And so the experts played well. Including the Omicron brand in the shooting felt necessary, because of the number of the virus changes. But going to Omicron seemed risky — some experts worried that “the bug would go back,” Subbarao told me, to a brand like Alpha or Delta or something. As a compromise, several countries, including the United States, went with the combination: half original, half Omicron, in an attempt to restore the OG protection and put a new protection on the surrounding problems.

And those fireworks he said strengthen the immune system that is already there, as it helps. But they haven’t sparked new responses against Omicron as some experts had hoped, Ott told me. Having already been educated about this virus, human bodies seem to have a myopic-raising again and again the defense against the ancient species, at the expense of innovation that could seriously damage Omicron. The results are not considered harmful, Subbarao told me: The bivalent, for example, increased the immunity of people against SARS-CoV-2 compared to, say, another dose of the first shot, and it was. staff by reducing hospitalization rates. But Ahmed told me that, in retrospect, he thinks Omicron’s only boost would be to rekindle the momentum it already has.

Heavy fatigue on XBB.1 can now prevent a world from falling into the same trap twice. People who are shot in a modified form of the challenge only receive the new, unknown mixture, which allows the immune system to focus on new things and be able to get out of the parent problems. XBB.1’s spike protein also cannot be dissolved by one from the old models – a concern Ahmed has with this shot. When researchers added Omicron to their vaccine recipes, they it did not double the amount of spike protein; they released half of what was already there. Vaccinates who were left with only half of the Omicron-targeted mRNA would have had less of a shot, and possibly a stronger antibody response.

Recent jobs from the lab of Vineet Menachery, a virologist at the University of Texas Medical Branch, suggests another reason why the Omicron half-shot didn’t pack enough of a vaccine punch. Followers of this type, including BA.5 and XBB.1, carry one mutation that makes their spike protein unstable—to the point where it appears less likely than other types of spike protein to stick around long enough to go to school. immune cells. In bivalent vaccines, in particular, the immune response can be accompanied by non-Omicron ingredients, increasing the tendency of previously vaccinated individuals to focus their efforts on the parent strain. For the same reasons, the stable XBB.1, too, may not provide the expected vaccine, Menachery told me. But if people take (he is still an adult if), and hospitalizations remain low among those recently vaccinated, a once-a-year change may be an option for next year’s vaccine as well.

Removing parental complications from vaccines is not dangerous. The virus could also produce a different version of XBB.1, although this, at this point, seems unlikely. For a year and a half now, Omicron has endured, and now has the longest run of Greek letters since the outbreak. Even the smallest ones in the Omicron family seem to grow on each other in a familiar way; After long disagreements, the evolution of the virus now appears to be a “small leap,” said Leo Poon, a virologist at the University of Hong Kong. It may be a sign that humans and the virus have reached their peak now that the population is covered with sufficient immunity. In addition, even if a stray Alpha or Delta descendant wakes up, the world will never know: Most people have bank protection against this and other previous ones so they would still be protected from the evils of COVID. bad results. (That guarantee does not apply, however, to people who still need the first shot, including babies born in the world every day. The increase in XBB.1 may be a good option for people with adequate immunity. But bivalents that can provide more coverage may be a poor choice risk to a person whose immunological slate is blank.)

Vaccines—a revolutionary method will undoubtedly come. SARS-CoV-2 is still new to us; so is our shooting. But the evolution of the virus, as of late, has been more flu-like, and its mode of transmission has a significant impact on the weather. US regulators have already announced that the COVID vaccine will may be given annually in the fall-as in annual shots. Viruses are not all the same. But as the years go by, the comparison between the COVID shot and the flu may be appropriate, say, the coronavirus also starts releasing multiple, different strains that circulate at the same time. In such cases, vaccination against multiple viruses at the same time may be the most effective method of protection.

The flu shot can be a useful template in another way: Although the shot has followed the same guidelines for many years, experts meet twice a year to decide and how to change the ingredients of the autumn vaccine, they also need to be flexible. . Until 2012, these vaccines were small, with combinations that could vaccinate people against three different strains at once; now many, including all of the US, are quadrivalent—and soon, based on new evidence, researchers. can push them back to the three-way path. At the same time, the flu vaccine and COVID share a major problem. The ingredients we inject are still selected months before the vaccine actually reaches us—leaving the immune system to lag behind the virus that, over time, rushes forward. Until the world has something universal, our vaccination methods must be conservative, rushing to adapt to the evolution of these pathogens.

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