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What we know and don’t know about virus variants and vaccines


 

About 20 states across the country have detected the more transmissible B.1.1.7 SARS-CoV-2 variant to date. Given the unknowns of the emerging situation, experts with the Infectious Diseases Society of America addressed vaccine effectiveness, how well equipped the United States is to track new mutations, and shared their impressions of President Joe Biden’s COVID-19 executive orders.

One of the major concerns remains the ability of COVID-19 vaccines to work on new strains. “All of our vaccines target the spike protein and try to elicit neutralizing antibodies that bind to that protein,” Mirella Salvatore, MD, assistant professor of medicine and population health sciences at Weill Cornell Medicine, New York, said during an IDSA press briefing on Thursday.

The B.1.1.7 mutation occurs in the “very important” spike protein, a component of the SARS-CoV-2 virus necessary for binding, which allows the virus to enter cells, added Dr. Salvatore, an IDSA fellow.

The evidence suggests that SARS-CoV-2 should be capable of producing one or two mutations per month. However, the B.1.1.7 variant surprised investigators in the United Kingdom when they first discovered the strain had 17 mutations, Dr. Salvatore said.

It’s still unknown why this particular strain is more transmissible, but Dr. Salvatore speculated that the mutation gives the virus an advantage and increases binding, allowing it to enter cells more easily. She added that the mutations might have arisen among immunocompromised people infected with SARS-CoV-2, but “that is just a hypothesis.”

On a positive note, Kathryn M. Edwards, MD, another IDSA fellow, explained at the briefing that the existing vaccines target more than one location on the virus’ spike protein. Therefore, “if there is a mutation that changes one structure of the spike protein, there will be other areas where the binding can occur.”

This polyclonal response “is why the vaccine can still be effective against this virus,” added Dr. Edwards, scientific director of the Vanderbilt Vaccine Research Program and professor of pediatrics at Vanderbilt University, Nashville, Tenn.

Dr. Salvatore emphasized that, although the new variant is more transmissible, it doesn’t appear to be more lethal. “This might affect overall mortality but not for the individual who gets the infection.”

Staying one step ahead

When asked for assurance that COVID-19 vaccines will work against emerging variants, Dr. Edwards said, “It may be we will have to change the vaccine so it is more responsive to new variants, but at this point that does not seem to be the case.”

Should the vaccines require an update, the messenger RNA vaccines have an advantage – researchers can rapidly revise them. “All you need to do is put all the little nucleotides together,” Dr. Edwards said.

“A number of us are looking at how this will work, and we look to influenza,” she added. Dr. Edwards drew an analogy to choosing – and sometimes updating – the influenza strains each year for the annual flu vaccine. With appropriate funding, the same system could be replicated to address any evolving changes to SARS-CoV-2.

On funding, Dr. Salvatore said more money would be required to optimize the surveillance system for emerging strains in the United States.

“We actually have this system – there is a wonderful network that sequences the influenza strains,” she said. “The structure exists, we just need the funding.”

“The CDC is getting the system tooled up to get more viruses to be sequenced,” Dr. Edwards said.

Both experts praised the CDC for its website with up-to-date surveillance information on emerging strains of SARS-CoV-2.

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