Paul Goepfert, Professor of Medicine in the UAB Division of Infectious Diseases. "I think the worry is that if the virus keeps mutating, maybe the vaccine is not going to continue to do well against that, but I suspect that we're still going to do very well against severe disease and hospitalization," said Dr. Those fully vaccinated with at least the primary series were five times less likely to die from COVID in the summer of 2022, according to the Centers for Disease Control and Prevention. "The omicron spike protein is very, very different from the spike protein in the current vaccine."īut even when facing new variants, studies show the original booster continued to reduce the risk of severe illness from COVID-19. Anna Durbin, director, center for immunization research Johns Hopkins Bloomberg School of Public Health. "When we have an omicron-specific booster, it doesn't make sense not to use that," said Dr. These boosters are specifically designed against new omicron sub variants BA.4 and BA.5. Meanwhile, updated boosters are slated to roll out this week. Boosters, they argue, will not freeze the immune system in place. Other scientists disagree, arguing the immune system is adaptable and dynamic. Paul Offit, professor of pediatrics at Children's Hospital Philadelphia. It makes it harder for them to respond then to essentially a completely different virus," says Dr. "Where this matters is if you keep giving booster doses with strain, and continue to lock people into that original response. At this point in the pandemic, some adults have received four or more doses of the same vaccine.Īlthough still theoretical, some scientists worry about a potential backfire, with frequent boosting handcuffing the body's natural immune system and leaving it exposed to radically different variants that might emerge in the future. Some experts say they are concerned that frequent boosting with the original version of the vaccine may have inadvertently exacerbated immune imprinting. What does this all mean in terms of COVID vaccines and boosters? Dan Barouch, director of the center for virology and vaccine research at Beth Israel Deaconess Medical Center. "In other words, the first antigens that you're exposed to the ones your immune system is most trained to recognize and respond to more strongly the next time," said Dr. But the virus has continued to shape-shift, evolving into new variants that are still recognizable, but slightly different from predecessors. The human immune system's best playbook is against an invader it already knows, experts say. "There's a theory that our immunological response to the first exposure to a virus may sort of imprint your immune system," said John Brownstein, an ABC News contributor and chief innovation officer at Boston Children's Hospital. This is the main reason why seasonal influenza vaccines are updated frequently, to maintain protection in risk groups against currently circulating strains (Arinaminpathy & Grenfell, 2010).What is original antigenic sin or immunological imprinting? When a type A virus undergoes both kinds of changes, it is capable of evading host immunity, with profound implications for epidemiology and control. Since the late nineteenth century, four occurrences of antigenic shift have led to major influenza pandemics.Īlthough influenza viruses constantly and gradually change by antigenic drift, antigenic shift happens only occasionally. An antigenic shift can lead to a worldwide pandemic if the virus is efficiently transmitted from person to person.Īn example of a “shift” occurred in the spring of 2009, when a novel H1N1 virus with a new combination of genes (from American pigs, Eurasian pigs, birds, and humans) emerged in people and quickly spread, causing a pandemic. Source: Griffinstorm, Wikipedia Commons.Īntigenic shift results in a new influenza A subtype that is so different from previous subtypes in humans that most people do not have immunity to the new virus. Like this lightning storm near New Boston, Texas, antigenic shift involves major, abrupt changes in surface antigens (HA or NA).
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