With a particularly strong strain of influenza going around this winter, a chain of hospitals in Michigan instituted a rule to limit exposure for young children. Until flu season is over, the Beaumont chain of hospitals in and around Detroit will not allow visitors under the age of 13, the Detroit Free Press reported.

The move came in the wake of a flu season that saw 20 children die from the H3N2 strain of influenza that has been common this winter. Beaumont announced it would not let in kids younger than 13 due to the high volume of flu patients, except for in cases where a parent or sibling may be near death. It is only a temporary measure until the flu subsides.

Beaumont also noted children who have not shown any symptoms could still carry the flu virus and unknowingly get patients sick. The Beaumont website has a long post detailing methods to prevent and protect children from the flu in the winter, including diligent hand-washing and making sure to get them vaccinated.

The Free Press said 46 states have seen a rise in flu victims recently. The H3N2 strain is the predominant form hospitals have seen this season, and it is known as a particularly severe version of influenza that tends to lead to increased numbers of hospitalizations, according to the Miami Herald. The Herald’s report indicated flu season is likely at its peak right now, but that does not mean it is close to over just yet.