Modeling the potential impact of vaccination on the epidemiology of congenital cytomegalovirus infection.

BACKGROUND: Understanding the potential for vaccination to change cytomegalovirus (CMV) epidemiology is important for developing CMV vaccines and designing clinical trials. METHODS: We constructed a deterministic, age-specific and time-dependent mathematical model of pathogen transmission, parameterized using CMV seroprevalence from the United States and Brazil, to predict the impact of vaccination on congenital CMV infection. FINDINGS: Concurrent vaccination of young children and adolescents would result in the greatest reductions in congenital CMV infections in populations with moderate and high baseline maternal seroprevalence. Such a vaccination strategy, assuming 70% vaccine efficacy, 90% coverage and 5-year duration of protection, could ultimately prevent 30-50% of congenital CMV infections. At equilibrium, this strategy could result in a 30% reduction in congenital CMV infections due to primary maternal infection in the United States but a 3% increase in Brazil. The potential for an increase in congenital CMV infections due to primary maternal infections in Brazil was not predicted with use of a vaccine that confers protection for greater than 5 years. INTERPRETATION: Modeling suggests that vaccination strategies that include young children will result in greater declines in congenital CMV infection than those restricted to adolescents or women of reproductive age. Our study highlights the critical need for better understanding of the relative contribution of type of maternal infection to congenital CMV infection and disease, the main focus of vaccine prevention.

Comparing active and passive varicella surveillance in Philadelphia, 2005-2010: recommendations for the transition to nationwide passive varicella disease surveillance.

OBJECTIVE: The Philadelphia Department of Public Health (PDPH) conducts active surveillance for varicella in West Philadelphia. For its approximately 300 active surveillance sites, PDPH mandates biweekly reports of varicella (including zero cases) and performs intensive case investigations. Elsewhere in Philadelphia, surveillance sites passively report varicella cases, and abbreviated investigations are conducted. We used active varicella surveillance program data to inform the transition to nationwide passive varicella surveillance. METHODS: We compared classification of reported cases, varicella disease incidence, and reporting completeness for active and passive surveillance areas for 2005-2010. We assessed reporting completeness using capture-recapture analysis of 2- to 18-year-old cases reported by schools/daycare centers and health-care providers. RESULTS: From 2005 to 2010, PDPH received 3,280 passive and 969 active surveillance varicella case reports. Most passive surveillance reports were classified as probable cases (18% confirmed, 56% probable, and 26% excluded), whereas nearly all of the active surveillance reports were either confirmed or excluded (36% confirmed, 11% probable, and 53% excluded). Overall incidence rates calculated using confirmed/probable cases were similar in the active and passive surveillance areas. Detection of laboratory-confirmed, breakthrough, and moderate-to-severe cases was equivalent for both surveillance areas. CONCLUSIONS: Although active surveillance for varicella results in better classified cases, passive surveillance provides comparable data for monitoring disease trends in breakthrough and moderate-to-severe varicella. To further improve passive surveillance in the two-dose-varicella vaccine era, jurisdictions should consider conducting periodic enhanced surveillance, encouraging laboratory testing, and collecting additional varicella-specific variables for passive surveillance.