The number of flu-related deaths in Indiana jumped to 21 on Monday.
The state health department says that two children are among those who have succumbed to the illness, which has infected thousands across the country.
This year's flu vaccine protects against the three most common strains of influenza and officials say that currently there is no shortage.
Those 6 months and older are urged to get vaccinated.
Symptoms of the flu include a fever of 100 degrees or higher, headache, fatigue, cough, muscle aches and sore throat.