Image of Anthony Fauci, director of NIAID; Image credit: NIAID

Unchecked COVID-19 transmission among the unvaccinated could cause problems for the vaccinated, a top federal health official says. 

The SARS-CoV-2 virus continues to circulate at a high rate in U.S. regions where vaccination is relatively low. Along with higher transmission and more severe illness, this unbridled viral spread could lead to more genetic mutation and new, stronger variants, according to Anthony Fauci, M.D., the director of the National Institute of Allergy and Infectious Diseases. 

“There’s a tenet that everybody knows in virology. A virus will not mutate unless you allow it to replicate,” he told NBC’s Meet the Press on Sunday. “So, if you allow the virus to freely circulate and not try and stop it, sooner or later there is a likelihood that you will get another variant that could, I’m not saying it will, that could be more problematic than the delta.”

As currently formulated, COVID-19 vaccines do a good job of protecting recipients against the latest and most concerning delta variant, he said. But if the virus is given the chance to change due to rampant transmission, a worse variant has a better chance of taking hold, he cautioned. “And then, that will impact not only the unvaccinated; that will impact the vaccinated,” he said. 

Vaccinated residents succumb to new variant

In Belgium, a new strain appears to have done just that. The B.1.621 variant, first found in Colombia, made it into an eldercare facility in the town of Zaventem, near Brussels, Reuters has reported.

Two people living in a dementia care unit tested positive for the virus and were quarantined. But the infection eventually spread to 20 residents, according to NewsWeek. Seven residents in their 80s and 90s subsequently died — despite being vaccinated. 

Some of the residents who died were in poor health and at risk of severe outcomes, an administrator told the news outlet. One was terminally ill and another was receiving palliative care. But others were in relatively good health, she said.

It is not yet known how transmissible the B.1.621 variant is, said virologist Marc Van Ranst, of the University of Leuven, whose team conducted tests in the facility. The variant only recently has landed in the United States, accounting for 10% of cases in South Florida in late July, according to Washington Post sources. It has been designated a “variant of interest” — among others — by the European Center for Disease Prevention and Control, and is on the World Health Organization’s alert list for further monitoring. But it is not prevalent in Belgium.

Such new variant threats are why getting shots to the unvaccinated remains critical, Fauci said.

“People who are unvaccinated should think about their own health [and] that of their family, but also the community responsibility to crush this virus before it becomes even worse,” he told Meet the Press.