MINNEAPOLIS — Minnesota health officials suspect that a coronavirus variant is driving a recent increase in the state’s case rate.

Infectious Disease Director Kris Ehresmann said during a media briefing Friday that more than 300 cases of the B117 variant first detected in the United Kingdom have been found in Minnesota. Cases have been detected in various parts of the state, including in Carver County near the Twin Cities, Mankato and St. Louis County, in the northern part of the state.

Health officials called virus variants a “significant cause for concern,” and expect the B117 mutation to eventually become the dominant strain in the state and country. As Minnesota continues with its vaccination efforts, officials warned against ceasing mitigation efforts like masking and social distancing to avoid further transmission of the more contagious variant.

“I can’t emphasize this point enough,” Ehresmann said. “We are in a race between the variants and the vaccine, and the decisions we all make in the next few weeks will have a lot to say about this race.”

The Minnesota Department of Health on Friday reported nine more COVID-19 deaths and 1,449 more cases, pushing the state’s pandemic totals to 6,771 deaths and 502,893 cases. While the statewide positivity rate of 4.2% remains under the state’s caution threshold, health officials are concerned because it has steadily ticked up in recent weeks.

As the weather gets warmer, officials warn against gathering for holidays such as Easter, Ramadan and Passover or traveling for spring break.

According to the state’s vaccine dashboard, more than 1.3 million Minnesotans had received at least one dose of coronavirus vaccine and more than 788,000 had been fully inoculated as of Wednesday.

The state is expecting to have more than 151,000 doses next week to administer to people around the state. Gov. Tim Walz said Friday on WCCO Radio that the state is expecting to receive a weekly allotment of 350,000 doses as soon as March 29.