The concept of bivalent vaccines aimed at protecting against two different strains of a virus is not new. The ongoing viral mutations are why antibodies produced in response to the original vaccine strains have over time become less effective at fending off infections by new variants. In this respect, the SARS-CoV-2 virus acts like a chameleon – a master of disguise – by changing its body configuration and escaping recognition by the immune system. The spike protein triggers the production of so-called neutralizing antibodies, which bind to the spike protein and prevent the virus from invading other cells.īut when the virus mutates, as we know that it does, the antibodies that were previously produced in response to the virus can no longer effectively bind to the newly mutated spike protein. In an actual COVID-19 infection, the SARS-CoV-2 virus uses its protruding spike protein to latch onto human cells and gain entry into cells. How does a bivalent vaccine trigger an immune response? The inability of the original vaccine strains to prevent reinfection and to trigger long-term protective immunity prompted the need for the reformulated vaccines. In the U.S., currently 89% of COVID-19 infections are caused by BA.5 and 11% are caused by BA.4. The key difference between the original COVID-19 shots and the new “bivalent” version is that the latter consists of a mixture of mRNA that encodes the spike proteins of both the original SARS-CoV-2 virus and the more recent omicron subvariants, BA.4 and BA.5.Īs of late August 2022, the BA.4 and BA.5 omicron subvariants are dominant worldwide. They use the same mRNA technology as the original vaccines. The newly authorized shots are the first updates to the original COVID-19 vaccines that were introduced in late 2020. What is different about the updated booster shots? They weigh in on how the updated booster shots train the immune system and how protective they might be against COVID-19. Prakash Nagarkatti and Mitzi Nagarkatti are immunologists who study infectious disorders and how vaccines trigger different aspects of the immune system to fight infection. But booster shots have proven to be an essential layer of protection against COVID-19. These low numbers may in part be influenced by people waiting for the newer versions of the vaccines to provide better protection. have received their first booster shot, and just under 34% of those eligible have received their second. 31, 2022, only 48.5% of booster-eligible people in the U.S. Anthony Fauci discusses approval of updated COVID booster shots that target omicronĪs of Aug. The new booster shots – one by Moderna and another from Pfizer-BioNTech – come as more than 450 people are still dying of COVID-19 every day in the U.S. The CDC’s backing will enable a full roll-out of the reformulated vaccines to begin within days. The decision comes just a day after the Food and Drug Administration’s emergency use authorization of the shots. 1, 2022, the Centers for Disease Control and Prevention endorsed the use of updated COVID-19 booster shots that are specifically tailored to combat the two most prevalent omicron subvariants, BA.4 and BA.5.
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