Doctors in Michigan and Indiana are reporting the first cases of the flu for the season.

Doctors with the CDC say there are a growing number of cases nationwide, but the vaccine appears to be strong this season.

Different strains are dominating certain parts of the country, and as people travel for the holidays doctors recommend taking precautions, including getting their flu shot.

Families headed to the southern states are said to be at the greatest risk. Michigan has seen a few cases and the state is listed as having “local activity,” meaning only the western part of the state is seeing outbreak activity. Indiana’s activity is more widespread, and listed as “regional.”