Vaccine researchers at Washington University said patients this fall could get an updated version of the COVID-19 shot.

The scientists are conducting a clinical trial of a new version of the original Moderna vaccine. Researchers say it will likely be better suited to newer BA.4 and BA.5 variants of the virus that have become dominant this summer.

The current vaccine is based on the original virus that emerged in 2019.

The coronavirus has continually changed to infect people more quickly and easily, said Dr. Rachel Presti, a Washington University infectious disease professor and a researcher for the Moderna clinical trial. Spike proteins on the surface of the virus have changed to better invade cells.

The second-generation vaccines being tested in patients are similar to what’s already available but help prepare the body for those changed spikes on the virus, Presti said.

“If we can update that immunity to match the virus better, the hope is that this will become a milder infection and will become more and more like the common cold,” she said.

The vaccine being tested at Wash U is known as a bivalent vaccine, she explained. That means it protects against the original and new variants of the virus.

Moderna and another drug developer, Pfizer, have submitted their bivalent vaccines to the federal Food and Drug Administration for approval. Federal regulators say they can rely on safety testing for the original vaccines and mice studies, since the new shots are so similar to the ones originally rolled out in 2020.

The Biden administration plans to make the new versions of the vaccine available this fall.

It's possible that drug manufacturers will need to regularly rework the COVID-19 vaccine for the next few years to better match circulating versions of the virus, similar to how the annual flu vaccine is produced, Presti said.

“As long as we are still seeing severe infection, in some populations, there is a benefit to adjusting the vaccine to what's most likely to be around,” she said.

People are slowly becoming more comfortable with the idea of getting vaccinated against the coronavirus, said Dharushana Muthulingam, a St. Louis-based infectious disease physician.

“I think people already have this understanding of booster shots, often with their kids or when they were kids,” she said.

The biggest hurdle has always been availability, Muthulingam said.

“I think the novelty is probably less of an issue,” she said. “I still think the No. 1 thing is access to those boosters: Are people going to drive to Walgreens? Do they have a primary care doctor who can offer it to them? That’s always going to be the main bottleneck.”

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