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In reply to the discussion: So when do we cut out the anti vaccine idiots and start living our regular lives? [View all]GaYellowDawg
(4,443 posts)The new variants do NOT have "different spike proteins." They have amino acid substitutions in the spike protein. When mutations occur, they sometimes (not all the time) cause a change in the amino acid sequence during translation from mRNA into proteins. Sometimes, this will change the way that the protein folds, and therefore changes its shape. As the spike protein's shape determines its ability to bind to the ACE-2 receptor, any changes in that shape are much more likely to negatively affect its ability to bind. Therefore, there's a very limited number of mutations/variants of the spike protein that still allow the virus to be infectious.
The "narrowness," as you put it, of the vaccines is actually an extremely strong point in their favor. With an attenuated vaccine, such as the polio vaccine, the immune system won't recognize the entire virus. It will recognize portions of the virus, called epitopes. Each protein that makes up the viral capsule (the exterior) is potentially an epitope. This means that different individuals can develop immune responses to different proteins on different sections of the virus. In a virus with a slow mutation rate, that's not a problem. In a virus, such as influenza or coronavirus, which have higher mutation rates, strains will arise that will have differently shaped proteins in their capsules, which can then escape immune responses to older viral proteins with different shapes.
The COVID vaccines cause a type of immune cell called an antigen-presenting cell to manufacture copies of the spike protein and "show" them to helper T-cells, which begin a primary immune response resulting in a population of T-cells and B-cells specifically geared to react to the spike protein. In natural immunity, or with a vaccine with attenuated SARS-CoV-2, it may or may not be the spike protein that's the trigger for a subsequent immune response. If the immune response was directed against a protein that doesn't particularly need to retain its shape for viral infection and function, the individual in question would be very potentially vulnerable to a second infection. Because, as I mentioned before, the spike protein can't change shape much without losing its function, and because the spike protein is the only means for infection by SARS-CoV-2, a vaccine specific to the spike protein is a much more effective vaccine against COVID-19 than an attenuated virus vaccine would be.
The odds that a change in the protein will occur that both retain the ability to bind to the ACE-2 receptor and make such significant changes to the protein as to escape the secondary immune response in vaccinated individuals are so vanishingly small as to be just about impossible. In fact, there's no evidence to suggest that any known variant can cause anything other than a mild case of COVID-19, and that was entirely predictable.
Quotes about the Indian variants from Amesh Adaljia, assistant professor at Johns Hopkins University's Bloomberg School of Public Health, and Dr. Jeffrey Klausner, MD, clinical professor of preventive medicine at U.S.C.'s Keck School of Medicine:
"What's important to remember is that anytime we see these variants, vaccines still are able to prevent what matters: serious disease hospitalization and death," says Adaljia. "The bottom line is that our vaccines induce not just antibodies but also T cell immunity. They are able to protect against the variants, even if they can get around the vaccine in terms of giving someone a mild infection. The solution to these variants is to vaccinate."
"You're going to keep seeing news about new variants because we are looking for new variants and sequencing new variants," says Dr. Klausner. "Be reassured that the current COVID-19 vaccines, particularly ones developed in the United States, still are highly effective against any variants."
The article with the quotes is here:
https://www.womenshealthmag.com/health/a36232744/what-is-triple-mutant-variant-coronavirus/
Also worth noting is that the CDC has not classified any COVID variant as a variant of high consequence:
https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/variant-surveillance/variant-info.html