The Centers for Disease Control and Prevention says 21 children have died of the flu this season, and city officials have now issued a mandate in hopes of preventing that number from climbing.

The city's Department of Health says flu vaccines are now mandatory for all children from 6 months to 5 years old who attend city-run day cares and preschools.

Dr. Eric Appelbaum, of Saint Barnabas Hospital, says the flu shot is only helpful when numbers prove that children are aided by it. He says an increase in vaccination rates in Connecticut show a decrease in hospitalization for the virus within the same population.

Part of the mandate states that if parents lack proof that their child has been vaccinated, their school can tell students to not show up until they receive the shot.

The Department of Health says that it may fine city-funded schools if any of their students are not vaccinated.