FDA/CDC

‘A few mutations away’: The threat of a vaccine-proof variant


 

The Centers for Disease Control and Prevention Director Rochelle Walensky, MD, MPH, made a dire prediction during a media briefing this week that, if we weren’t already living within the reality of the COVID-19 pandemic, would sound more like a pitch for a movie about a dystopian future.

Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention

Dr. Rochelle Walensky

“For the amount of virus circulating in this country right now largely among unvaccinated people, the largest concern that we in public health and science are worried about is that the virus … [becomes] a very transmissible virus that has the potential to evade our vaccines in terms of how it protects us from severe disease and death,” Dr. Walensky told reporters on July 27.

A new, more elusive variant could be “just a few mutations away,” she said.

“That’s a very prescient comment,” Lewis Nelson, MD, professor and clinical chair of emergency medicine and chief of the division of medical toxicology at Rutgers New Jersey Medical School in Newark, told this news organization.

“We’ve gone through a few mutations already that have been named, and each one of them gets a little more transmissible,” he said. “That’s normal, natural selection and what you would expect to happen as viruses mutate from one strain to another.”

“What we’ve mostly seen this virus do is evolve to become more infectious,” said Stuart Ray, MD, when also asked to comment. “That is the remarkable feature of Delta – that it is so infectious.”

He said that the SARS-CoV-2 has evolved largely as expected, at least so far. “The potential for this virus to mutate has been something that has been a concern from early on.”

“The viral evolution is a bit like a ticking clock. The more we allow infections to occur, the more likely changes will occur. When we have lots of people infected, we give more chances to the virus to diversify and then adapt to selective pressures,” said Dr. Ray, vice-chair of medicine for data integrity and analytics and professor in the division of infectious diseases at Johns Hopkins School of Medicine in Baltimore.

“The problem is if the virus changes in such a way that the spike protein – which the antibodies from the vaccine are directed against – are no longer effective at binding and destroying the virus, and the virus escapes immune surveillance,” Dr. Nelson said.

If this occurs, he added, “we will have an ineffective vaccine, essentially. And we’ll be back to where we were last March with a brand-new disease.”

Technology to the rescue?

The flexibility of mRNA vaccines is one potential solution. These vaccines could be more easily and quickly adapted to respond to a new, more vaccine-elusive variant.

“That’s absolutely reassuring,” Dr. Nelson said. For example, if a mutation changes the spike protein and vaccines no longer recognize it, a manufacturer could identify the new protein and incorporate that in a new mRNA vaccine.

“The problem is that some people are not taking the current vaccine,” he added. “I’m not sure what is going to make them take the next vaccine.”

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