Incidence rates of neurotropic-like and viscerotropic-like disease in three dengue-endemic countries: Mexico, Brazil, and Malaysia.

BACKGROUND: The background incidence of viscerotropic- (VLD) and neurotropic-like disease (NLD) unrelated to immunization in dengue-endemic countries is currently unknown. METHODS: This retrospective population-based analysis estimated crude and standardized incidences of VLD and NLD in twelve hospitals in Brazil (n = 3), Mexico (n = 3), and Malaysia (n = 6) over a 1-year period before the introduction of the tetravalent dengue vaccine. Catchment areas were estimated using publicly available population census information and administrative data. The denominator population for incidence rates was calculated, and sensitivity analyses assessed the impact of important assumptions. RESULTS: Total cases adjudicated as definite VLD were 5, 57, and 56 in Brazil, Mexico, and Malaysia, respectively. Total cases adjudicated as definite NLD were 103, 29, and 26 in Brazil, Mexico, and Malaysia, respectively. Crude incidence rates of cases adjudicated as definite VLD in Brazil, Mexico, and Malaysia were 1.17, 2.60, and 1.48 per 100,000 person-years, respectively. Crude incidence rates of cases adjudicated as definite NLD in Brazil, Mexico, and Malaysia were 4.45, 1.32, and 0.69 per 100,000 person-years, respectively. CONCLUSIONS: Background incidence estimates of VLD and NLD obtained in Mexico, Brazil, and Malaysia could provide context for cases occurring after the introduction of the tetravalent dengue vaccine.

Modelling Hospitalisation Ratios for Febrile Convulsions and Severe Varicella Under Combined Measles, Mumps, Rubella, and Varicella (MMRV-Priorix-Tetra™) Compared to Separate MMR + V Vaccination.

INTRODUCTION: Measles, mumps, rubella, and varicella combination vaccines (MMRV) facilitate varicella vaccination uptake compared with separate administration of measles, mumps, and rubella vaccine (MMR) with varicella vaccine (V). However, the risk of developing febrile convulsions (FC) is higher in children vaccinated with MMRV. OBJECTIVES: The aim was to demonstrate how to put the increased FC risk associated with MMRV into perspective by comparing it with the lower V-coverage risk associated with MMR + V. METHODS: FC and varicella burdens were measured by total numbers or duration of hospitalisations. A model, based on several assumptions and integrating parameters from heterogeneous data sources relevant to Germany, was developed to evaluate hospitalisation ratios (HRs; ratios between yearly numbers of varicella-related hospitalisation days prevented by MMRV and yearly numbers of FC-related hospitalisation days attributed to MMRV, both compared with MMR + V). A sensitivity analysis estimated HR under different scenarios beyond the German experience. RESULTS: For parameter values compatible with the German experience, where MMRV (Priorix-Tetra™, GSK, Belgium) was introduced in 2006, the model predicted that transitioning from MMR + V to MMRV would induce 225 vaccine-related FC hospitalisation days whilst preventing 1976 varicella-related hospitalisation days per year. The HR estimated by Monte Carlo simulations was 8.5 (95 % confidence interval: 1.99-25.22). A sensitivity analysis on two key parameters suggested that transitioning from MMR + V to MMRV would be favourable in situations where MMRV use would significantly impact varicella vaccination uptake. CONCLUSIONS: MMRV use instead of MMR + V can substantially reduce the number of hospitalisation days, despite increased FC risk when MMRV is used as a first dose of measles-containing vaccine.

The effectiveness of varicella vaccination in children in Germany: a case-control study.

BACKGROUND: Effectiveness of 1 dose of varicella vaccination was estimated to be 85-88% against clinical varicella of any severity in case-control studies in non-European countries, but lower effectiveness has been demonstrated in outbreaks. METHODS: A prospective, age- and practice-matched case-control study was conducted in Germany to assess the effectiveness of 1 dose of OKA/GSK varicella vaccine (derived from the OKA strain, a Japanese clinical isolate) and of any varicella vaccine (including OKA/GSK, OKA/Merck and MMR-OKA/GSK) against polymerase chain reaction (PCR)-confirmed varicella under conditions of routine use. RESULTS: The cohort included 432 PCR-confirmed cases and 432 matched controls (1-7 years old). Varicella vaccination was reported for 13.2% (57/432) of cases and 45.1% (195/432) of controls. Median time since vaccination was 28 and 25 months, respectively. Vaccinated cases experienced milder disease (P < 0.0001) and shorter duration of disease (P = 0.004) compared with unvaccinated cases. After adjusting for gender and school/day-care attendance, vaccine effectiveness of 1 dose of OKA/GSK against PCR-confirmed varicella of any severity was 71.5% (95% confidence interval [CI]: 49.1-84.0) and 94.7% (95% CI: 77.8-98.7) against PCR-confirmed moderate or severe varicella. Adjusted effectiveness for any varicella vaccine was 86.4% (95% CI: 77.3-91.8) against any severity and 97.7% (95% CI: 90.5-99.4) against moderate or severe varicella. CONCLUSIONS: One dose of varicella vaccine provided high protection against moderate and severe varicella disease for a period of up to 5 years after vaccination. However, further effectiveness data are needed to assess long-term protection.