Study shows influenza vaccine effectiveness for young children

A Finnish research study has presented promising data that may show the effectiveness of flu vaccines for younger children, which they hope will prompt countries to immunize children between the ages of six and 35 months.

The United States and Finland are currently among the few countries that recommend flu vaccination for children under two years of age, CIDRAP News reports.

A nonrandomized, prospective cohort trial found that the vaccine was 66 percent effective in children younger than three years old and that vaccination was not accompanied by adverse events. The trial was conducted during the 2007-2008 flu season in Turku, Finland. This was the first year following the country's with a 0.5 mL dose universal flu vaccination recommendation for children between the ages of six to 35 months.

The flu vaccination was free at local health centers and was effective against influenza A/H1N1 and H3N2, though not as effective against the influenza B subtype, CIDRAP News reports. Effectiveness against type A was found to be 84 percent, while effectiveness against type B was 45 percent, according to the study.

Influenza type A or B was confirmed in 7 of 154 fully vaccinated children and was confirmed in 61 unvaccinated children in the study.

Only four percent of vaccinated children under the age of two contracted the disease, while 12 percent of the unvaccinated children contracted either type of flu.

“These finding are clinically important, because the burden of influenza is particularly high among the youngest children, and hence both the need for and the benefit from an effective vaccine would be greatest in this age group,” the authors wrote, according to CIDRAP News. “Our findings are in stark contrast with the belief in many countries that influenza vaccines have poor effectiveness in children younger than two years.”