Home News The Covid Virus Keeps Evolving. Why Haven’t Vaccines?

The Covid Virus Keeps Evolving. Why Haven’t Vaccines?


March 16, In 2020, just 63 days after the company generated a genetic blueprint for the new virus, the first volunteer received Moderna’s then-experimental Covid-19 vaccine. But Moderna’s rivals beat it in the market: Pfizer’s Covid vaccine will be approved for use in the U.S. in less than a year, a record achievement. Previously, the fastest vaccine to develop was the mumps vaccine – which took about four years.

The speed at which the two companies were able to deliver the vaccine can be attributed to mRNA technology. Instead of using the virus itself to stimulate an immune response, as old vaccines did, scientists used a programmable genetic code called mRNA to stimulate it. The mRNA tells the body to make a spike protein unique to the coronavirus, so it can make antibodies to neutralize the spike protein. The mRNA is quickly broken down, but the memory of the spike protein lingers in the immune system, so it’s ready to attack if it encounters it again.

The promise of mRNA technology lies in its adaptability. Vaccine makers tout its plug-and-play nature. If the virus mutates to evade current vaccines, scientists can simply swap in a new piece of mRNA to match the new version of the virus. But today, despite waves of variants including Delta, Omicron and the latest threats (Omicron sub-variants BA.4 and BA.5), Covid-19 vaccines and boosters are still targeting late 2019 discoveries original virus. Why not? t variant-specific boosters arriving earlier?

“You’re dealing with a virus that’s mutating rapidly. Each of those variants exists for a few months and then gets replaced by a new variant,” said Archana Chatterjee, an infectious disease specialist at the School of Medicine of Chicago. “It’s a game where we’ve been behind.”

BA.4 and BA.5 are by far the fastest movers. “In these two years, the virus has become more contagious,” continued Chatterjee, who is also a member of the Vaccine and Related Biologicals Advisory Committee (VRBPAC), an independent panel of experts that advises the United States Food and Drug Administration.

Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, told the VRBPAC meeting on June 28 that while currently available vaccines have greatly reduced deaths and hospitalizations from Covid-19, “their effectiveness does appear to vary with weakened over time.” The initial booster shots helped restore some protection against severe disease, but their effectiveness also appears to be waning.

In June, all of these factors led VRBPAC to recommend that vaccine manufacturers update their fall and winter 2022 Covid booster vaccines to accommodate the BA.4 and BA.5 subvariables. Those subvariables appear to be driving a new wave of hospitalizations in the U.S. and U.K., based on the evidence, Chatterjee said. The U.S. government intends to buy millions of variant-specific doses for fall booster campaigns.

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