LANSING, Mich. (AP) — Michigan Gov. Gretchen Whitmer’s administration on Monday lengthened, by 12 days, a partial shutdown of businesses and schools to curb the coronavirus.

The extended order, now due to end Dec. 20, will enable the state health department to assess how Thanksgiving travel affected the spread of COVID-19, the Democratic governor said.

In-person instruction at high schools, dine-in eating at restaurants and organized sports will continue to be prohibited. Entertainment venues like movie theaters and bowling alleys will stay closed.

“Hope is on the horizon, but we need an additional 12 days to determine the full impact of the Thanksgiving holiday on our efforts to mitigate the spread of the virus,” Whitmer said in a statement released at the start of a news conference. ”This is all about protecting our families and frontline workers until we eradicate this virus once and for all.”

The administration also identified three key metrics it will use to determine whether to slowly reopen after Dec. 20: the percentage of hospital beds with COVID-19 patients, the number of cases and the positivity rate. The first priority will be reopening high schools, then entertainment businesses where people can consistently wear masks such as casinos, theaters and bowling alleys, with concessions closed.