A health worker gives a homeless woman a shot of the Johnson & Johnson COVID-19 vaccine at a municipal homeless shelter in Bogota, Colombia, Friday, July 2, 2021. Credit: Fernando Vergara / AP

AUGUSTA, Maine — A new COVID-19 variant that has sparked concerns about possible vaccine resistance was detected in Maine early this summer, but it has not taken off here in another sign that it does not spread nearly as easily as the dominant strain.

The mu strain, first detected in Colombia, has made headlines in recent days after it was added to the World Health Organization’s list of “variants of interest” last week. But Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said last week that he does not think the new strain is an “immediate threat.”

It has been in Maine since at least May, according to state data. Since the emergence of the alpha variant last winter, Maine has sent a share of positive COVID-19 samples for genetic testing to determine whether they represent the original virus strain or a concerning variant.

Although the tested samples represent only a small percentage of COVID-19 cases in Maine, they still provide insight into the relative prevalence of different strains here. In June, the mu variant accounted for 11 percent of tested samples here, according to data from the Maine Center for Disease Control and Prevention.

That was a higher prevalence than the delta variant at that point. But the delta variant has taken off in Maine since then, accounting for nearly all tested samples in August and driving the overall surge in cases. The mu variant has not multiplied in the same way, consistent with patterns seen elsewhere, with officials in other countries saying the mu variant does not appear to be spreading nearly as fast as delta.

Health officials are still keeping an eye on the mu variant due to reports out of the United Kingdom that vaccines and treatment might be less effective in fighting it, although the public health agency there said more real-world data was needed.

Maine CDC Director Nirav Shah said Wednesday that there was not yet enough information to make pronouncements about the mu variant or what it might mean for the future of the pandemic. He added that combating the delta variant remained the priority here.

“If these variants are concerning to you, you’ve got a tool,” Shah said, “and that tool is to go get vaccinated.”