Surveillance for influenza in a newborn intensive care unit

Although influenza may cause fatal neonatal infections, the current prevalence of disease in newborn intensive care units (NICU) is unknown. Furthermore, because compliance of NICU staff with annual influenza immunization is poor, absence of antibody may provide an indication of influenza susceptibility for neonatal patients and staff. We studied our NICU staff and patients during the winter of 1992-93 to determine seroprevalence of influenza antibody and attempted to document infection serologically or by culture in symptomatic staff and by culture in neonatal patients. Before the influenza season commenced or at birth (using cord blood), antibody to influenza A was absent in 9% (4/43) of the staff and 11% (9/83) of the neonatal patients. Antibody to influenza B was absent in 26% (11/43) of the staff and in 37% (31/83) of the neonates. We were able to document influenza serologically in only one nurse during the study. None of our staff or patients had positive cultures; however, we demonstrated a susceptible population of both staff and particularly neonates who need protection. There were study limitations of sampling and a low incidence of influenza in Connecticut for 1993. Nevertheless, continuing surveillance for influenza in NICUs could provide a more rational basis for immunization and prevention practices.