U.S. medical experts have raised new concerns about the BA.2 Omicron sub-variant of the COVID-19. A third of U.S. COVID-19 cases have been identified as BA.2 sub-variant cases and current estimates suggest that the BA.2 variant is also 50% to 60% more infectious than the original Omicron variant.

As cases of the sub-variant rise in Europe amid a global relaxing of COVID-19 restrictions like required mask-wearing, vaccinations, and travel guidelines. However, many experts feel that restrictions may have been relaxed too early.

“It’s inevitable we will see a BA.2 wave here,” Dr. Eric Topo, head of Scripps Research Translational Institute told the Associated Press on Tuesday. “We’re not protected in this country compared to peer countries.”

In the past, waves of various COVID-19 variants have led to the U.S. having the highest number of cases and deaths in the world. The vaccination rate in the U.S. is also lower than in places like the U.K., Australia, New Zealand, and Canada. Only 66% of the U.S. population is fully vaccinated, which amounts to a full course of the original vaccine dose, not a booster.

Dr. Anthony Fauci told the Washington Post on Tuesday that while he “would not be surprised at all if we do see somewhat of an uptick,” he does not think, “that there will be a major surge.”

Fauci also stated that “we can’t claim absolute victory at this point. They’re still viral dynamics.”

This could be because so many more people now have contracted the virus and/or are vaccinated to protect themselves than at the start of the pandemic. That fact will supply some protection against mass hospitalizations and deaths, but will still put a significant amount of stress on hospitals and healthcare systems.

“The good news is that we got a huge Omicron surge in the U.S. Millions of people were infected," Dr. Carlos Del Rio, an infectious disease specialist and executive associate dean at the Emory School of Medicine, told CNN.

“Between the number of people infected and the number of people who were already vaccinated, we estimate that about 73% to 75% of the population has some degree of immunity," Dr. Del Rio said.

Though many experts do not predict a dramatic surge in the U.S., there are still 25% of Americans who have not been vaccinated and are vulnerable to the virus. That amounts to about 82 million people out of the 330 million population. Those 82 million still place a significant strain on healthcare systems and potential community spread.

“So the advice is proceed with life as normally as you possibly can, but be prepared that we might need to make modifications if things change,” Fauci said during the live interview, echoing a sentiment he has expressed before.

Illustration shows test tube labelled "COVID-19 Omicron variant test positive
Representation. Reuters / DADO RUVIC