Prevention of Influenza in Infants by Immunization of Their Contacts in the Household

Background:
When compared to other age groups, infants < 6 months are at higher risk for influenza complications. Because there is no currently licensed vaccine for this age cohort, prevention efforts should focus on vaccinating household contacts.

Objectives:
The purpose of this study was to develop and assess a program for administering influenza vaccine to household contacts of newborns delivering at a community hospital.

Methods:
Between October 2007 and February 2008 inactivated influenza vaccine was offered to new mothers and household contacts of newborns delivered at a Durham Regional Hospital located in NC. Promotional materials included a letter to new mothers, posters, and coupons for free influenza vaccine for household contacts. Standing influenza vaccine orders were implemented for postpartum women and a conveniently located vaccination clinic was established for household contacts. Vaccine reminders were mailed postpartum. Influenza vaccine coverage rates of household contacts were assessed using a face-to- face maternal interview with a follow-up telephone interview at 6 to 8 weeks.

Results:
During the study period, 890 women delivered 904 newborns. Of 364 women approached, 238 (65.4%) were interviewed and 194 (81.5%) had follow-up interviews. Vaccination rates for household contacts during the influenza season were as follows: mothers (69.6%), fathers (52.9%), siblings (52.0%), other relatives (31.6%) and non-relatives (25.0%). Among new mothers, 40.9% received vaccine during pregnancy. Of those not vaccinated before delivery, 45.0% were vaccinated in the hospital and 3.6% were vaccinated within 6 to 8 weeks after hospital discharge. Among new fathers, 22.3% received vaccine prior to the baby's birth and among those not vaccinated, 33.1% received vaccine during the baby's hospital stay and 6.2% received vaccine after hospital discharge.

Conclusions:
A hospital-based influenza vaccination program is an effective method of increasing immunization rates of household contacts of newborns, thereby protecting this vulnerable cohort from influenza exposure.