Pediatric Flu Vaccine Works Despite Strain Mismatch

Pediatric Flu Vaccine Works Despite Strain Mismatch


NEW YORK (Reuters Health) Mar 14 - Despite not being a good match for circulating influenza strains, flu vaccination still provides a considerable degree of protection in many young children, researchers report in the March issue of Pediatrics.

"The results of our investigation," Dr. Carrie M. Shuler told Reuters Health, "support recommendations for influenza vaccination of children and strengthen the evidence of the vaccine's ability to reduce substantially the burden of disease among children."

Dr. Shuler of the Georgia Department of Public Health, Atlanta and colleagues came to this conclusion after conducting a study of 290 children attending a single pediatric practice in the 2003 to 2004 flu season.

During this season, there was a less than ideal match between the vaccine and the predominantly influenza A (H3N2) viruses. Only 25% of the circulating viruses were similar antigenically to the vaccine strain in use.

To investigate what consequences this might have had, the children, all of whom had laboratory-confirmed influenza and were between 6 and 59 months old, were matched 1:2 with controls.

Compared with unvaccinated children, the efficacy of the vaccine in fully vaccinated children was 49%. Partially vaccinated children under the age of 23 months had no significant reduction in influenza. However, older partially vaccinated children showed a 65% reduction.

Thus, concluded Dr. Shuler, "we found that influenza vaccination provided protection against medically attended children who were aged 6 to 59 months during a season with a suboptimal match between vaccine and circulating strains."

Pediatrics 2007;119:e587-e595.