Mandatory Flu Vaccine for Daycare May Lower Hospitalizations

Janis C. Kelly

March 06, 2014

Requiring preschool children to have influenza vaccinations before they can attend daycare programs helped reduce serious influenza-related illnesses in this vulnerable population in Connecticut, according to data reported in the March 7 issue of the Morbidity and Mortality Weekly Report.

In September 2010, Connecticut became the second US state to require that children aged 6 to 59 months receive at least 1 dose of influenza vaccine each year to be able to attend a state-licensed child care program.

In the current study, James L. Hadler, MD, MPH, senior infectious disease and medical epidemiology consultant to the Connecticut Emerging Infections Program, and clinical professor of epidemiology (microbial diseases) at Yale School of Public Health, New Haven, Connecticut, and colleagues compared vaccination rates and influenza-related hospitalization rates for the 2009-2010 influenza season with those for the 2012-2013 influenza season.

The analysis included vaccination data from US and Connecticut surveys and the Emerging Infections Program. According to the authors, as of December 21, 2012, 55,640 children aged 6 to 59 months were enrolled in licensed Connecticut child care centers.

The researchers found that the vaccination rate for seasonal influenza increased from 67.8% during the season before the vaccination requirement took effect to 84.1% during the 2012-2013 season. This 16.3 percentage point increase was slightly larger than the 11.9 percentage point increase in national data from the same age group, but the difference did not reach statistical significance.

The increase to an 84.1% vaccination rate was associated with a 12% decrease in influenza-associated hospitalizations among children aged 4 years or younger. The ratio of influenza-associated hospitalization for these young children compared with the overall rate for all ages also dropped from 1.18 to 0.53.

The authors stressed not only that children aged 4 years or younger are at greater risk for severe influenza complications than older children but also that those in day care are at greater risk for influenza exposure and are likely to expose others outside the day care setting. The authors write, "Similar to other vaccine-preventable diseases that are spread by respiratory droplets and that affect children, achieving high vaccination rates against influenza in child care settings not only protects those who are vaccinated, but also reduces transmission of influenza within the setting and to the associated outside community."

They also point out the study's limitations, including potential confounding from other causes of decreased hospitalizations, lack of data from family day care homes or preschools, and Emerging Infections Program hospitalization rates that include children younger than 6 months, although children that young are not eligible for influenza vaccination.

The authors have disclosed no relevant financial relationships.

Morb Mortal Wkly Rep. 2014;63:181-185. Full text


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