Protecting newborns by immunizing family members in a hospital-based vaccine clinic: a successful Tdap cocooning program during the 2010 California pertussis epidemic.

OBJECTIVE: Infants are at greatest risk for mortality from pertussis infection. Since 2005, the Advisory Committee on Immunization Practices has recommended a cocooning strategy of vaccinating all close contacts of infants with tetanus, diptheria, and acellular pertussis (Tdap) vaccine to reduce the risk of transmitting pertussis. Difficulties in establishing a complete cocoon have been reported in the literature. We determined whether families of newborns could be fully immunized against pertussis, thereby providing a complete cocoon of protection.

METHODS: Tdap vaccine was offered during visiting hours to contacts aged 7 years and older and to postpartum patients who had not received Tdap vaccine during pregnancy. We then conducted retrospective phone interviews with randomly selected mothers (or other family members) to assess vaccination rates. We compared household vaccination rates during intervention and control periods and the demographic factors associated with Tdap vaccination of all members within the households.

RESULTS: During the intervention period, 243 postpartum patients and 1,287 other family members of newborns were immunized, with 84.8% of all family members receiving Tdap vaccination. Seventy-six percent of households reported a complete cocoon. In the control group, 52.2% of all family members received Tdap vaccination, and 29.3% of households had a complete cocoon. In the control group, fewer family members completed Tdap vaccination in the larger households than in the smaller households (p=0.008).

CONCLUSION: A cocooning strategy can be successfully implemented, such that the majority of newborns leave the hospital with their families fully immunized against pertussis.