The average vaccine coverage among healthy children of clusters assigned to the influenza vaccine was 83 percent, which was similar to the average vaccine coverage among colonies assigned to hepatitis A vaccine (79 percent). Laboratory-confirmed influenza was detected in 119 nonrecipients: 39 (3.1 percent) in the colonies assigned to influenza immunization and 80 (7.6 percent) in colonies assigned to hepatitis A. The level of indirect vaccine protective effectiveness was 61 percent.

Among all study participants (those who were and those who were not vaccinated), 80 of 1,773 (4.5 percent) in the influenza vaccine colonies and 159 of 1,500 (10.6 percent) in the hepatitis A vaccine colonies had confirmed influenza illness for an overall protective effectiveness of 59 percent. No serious vaccine adverse events were observed.

"Considering for instance the rapid spread of influenza A(H1N1) in the 2009 pandemic, understanding whether influenza transmission can be prevented or reduced by immunizing children is of high priority so that groups such as pregnant women and aboriginal populations who are at high risk of complications may potentially be indirectly protected," the authors write.

"Our findings offer experimental proof to support selective influenza immunization of school aged children with inactivated influenza vaccine to interrupt influenza transmission. Particularly, if there are constraints in quantity and delivery of vaccine, it may be advantageous to selectively immunize children in order to reduce community transmission of influenza." (JAMA. 2010;303[10]:943-950. Available pre-embargo to the media at www.jamamedia)

Source JAMA