LANSING, Mich. — The first known case of a new variant of the coronavirus was reported in Michigan, in a boy living in Jackson County.

The B.1.351 strain, first detected in South Africa in December, is believed to be more infectious. It shares some mutations with a B.1.1.7, a more easily spread variant that was first identified in Britain late last year and was found in Michigan in January.

The state health department said late Monday that an investigation was underway to determine the boy’s close contacts and if there are additional associated cases. Officials said there is no indication that the variant discovered in South Africa is more deadly or causes more severe illness. But higher transmission rates could increase hospitalizations and deaths should new variants spread widely.

“We are concerned about the discovery of another variant in Michigan, although it was not unexpected,” Dr. Joneigh Khaldun, chief medical executive and chief deputy director for health, said in a statement. “We continue to urge Michiganders to follow a research-based approach by wearing their masks properly, socially distancing, avoiding crowds, washing their hands often, and making a plan to get the safe and effective COVID-19 vaccine once it is their turn.”

Vaccines appear to be working against coronavirus variants.