No, the CDC didn’t say a new COVID strain is more contagious among vaccinated people than unvaccinated people

There has recently been an uptick in new COVID-19 hospital admissions in the past few weeks, although it’s still below peaks from the past few summers and winters. Health officials are closely monitoring the rise, particularly since wastewater surveillance has detected the presence of a new, highly transmissible subvariant of COVID-19 in the United States.

Multiple social media posts claim that the Centers for Disease Control and Prevention (CDC) says this new subvariant, BA.2.86, is more contagious in vaccinated people than it is in unvaccinated people.

THE QUESTION

Did the CDC say a new subvariant of COVID-19 is more contagious in vaccinated people than in unvaccinated people?

THE SOURCES

• Centers for Disease Control and Prevention (CDC)
• Yale Medicine
• UCHealth, a Colorado-based hospital network
• Data from the CDC and past studies on COVID-19 infectiousness among vaccinated and unvaccinated people

THE ANSWER

No, the CDC did not say a new subvariant of COVID-19 is more contagious in vaccinated people than in unvaccinated people.

WHAT WE FOUND

The Centers for Disease Control and Prevention (CDC) said BA.2.86, a new COVID-19 subvariant of omicron, might be more contagious as compared to previous variants in people who already have COVID-19 immunity. That includes both people who have previously been infected and people who have been vaccinated.

The CDC did not compare the subvariant’s transmissibility between vaccinated and unvaccinated people.

In the CDC’s Aug. 23 risk assessment for BA.2.86, the CDC said “BA.2.86 may be more capable of causing infection in people who have previously had COVID-19 or who have received COVID-19 vaccines.”

While the CDC didn’t specify in that sentence that it was comparing BA.2.86’s transmissibility to that of other strains, it did make that clarification further down in the risk assessment.

“The large number of mutations in this variant raises concerns of greater escape from existing immunity from vaccines and previous infections compared with other recent variants,” the CDC said.

In that same risk assessment, the CDC continued to recommend vaccines for protection from COVID-19 and said that the CDC’s current assessment is that the upcoming updated vaccine will be effective at reducing severe disease and hospitalization.

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An updated CDC assessment from Aug. 30 said that “scientists are evaluating how previous immunity from vaccinations or past infections protect against this new variant” and reiterated that the health agency believes the updated vaccine will “likely be effective at reducing severe disease and hospitalization.”

The CDC said the updated vaccine will be available to the general public “as early as mid-September.” It targets omicron subvariants of COVID-19, which would therefore include BA.2.86.

So far, only a handful of BA.2.86 cases across four states have been identified within the United States, the CDC says. That means the CDC lacks evidence to say with certainty exactly how BA.2.86 will respond to vaccines at this point in time. 

The reason the CDC is concerned that it could be more contagious than usual among vaccinated people compared to previous strains is because of the virus’s genetic makeup. BA.2.86 has many mutations that make it different from other COVID-19 strains, Yale Medicine says. Yale Medicine’s Scott Roberts, M.D., compared the difference to the one between the omicron and delta variants.

“When Omicron hit in the winter of 2021, there was a huge rise in COVID-19 cases because it was so different from the Delta variant, and it evaded immunity from both natural infection and vaccination,” Roberts said.

“It’s definitely part of the omicron family. But it looks pretty unique,” Michelle Barron, M.D., infectious disease specialist for Colorado-based hospital network UCHealth, said in a UCHealth article. “It may be different enough to where the immune system doesn’t recognize it as the virus.”

If the immune system doesn’t recognize the virus, it’s unlikely it will know how to fight it.

But because the updated COVID-19 vaccine is designed to fight against omicron descendants, which includes BA.2.86, UCHealth says the vaccine will likely provide some good protection against it. Additionally, Moderna announced on Sept. 6 that clinical trials indicate their updated vaccine generates a strong immune response to BA.2.86 and other circulating strains of COVID-19. The updated Moderna vaccine has not been approved by the FDA as of Sept. 6.

Barron told UCHealth that it’s typical for variants to appear strong, then sometimes disappear. That’s possible for BA.2.86, which means it could fizzle out before it has a chance to spread.

Data from the CDC indicates that COVID-19 vaccinations do reduce the likelihood of being infected by the disease, on top of reducing the likelihood of hospitalization and death. Previous studies have also suggested that COVID-19 is more contagious among unvaccinated people than it is among vaccinated people.