LANSING, Mich. — All people ages 16 and older in Michigan became eligible for COVID-19 vaccines on Monday, as the state passed the halfway point in its goal of inoculating 70% of that population by year’s end.

More than 35% of roughly 8.1 million residents had received at least one shot as of last week, a share that has tripled in two months. Federal regulators have not authorized vaccinations of children ages 15 and below, though clinical trials are underway.

Michigan continued to confront a surging case rate that was highest in the U.S. over the last two weeks.

In the Lansing area, the county health department recommended that middle and high schools suspend in-person learning when instruction resumes next week after spring break. Detroit’s K-12 district, which had spring break last week, said all students will learning online this week and next week. The city’s positivity rate was near 20% on Friday.