Sustained Effectiveness of Rotavirus Vaccine Against Very Severe Rotavirus Disease Through the Second Year of Life, Bolivia 2013-2014.

BACKGROUND: In Bolivia, monovalent rotavirus vaccine was introduced in 2008 and a previous evaluation reported a vaccine effectiveness (VE) of 77% with 2 doses of vaccine in children aged <3 years. This evaluation sought to determine if rotavirus vaccine provided protection through the second year of life against circulating genotypes. METHODS: A case-control study was performed in 5 hospitals from April 2013 to March 2014. Among enrolled participants who met study criteria and had rotavirus stool testing performed and vaccine status confirmed, we calculated VE using a logistic regression model. Subgroup analyses were performed among children aged <1 year and those aged ≥1 year, among children with severe diarrhea (Vesikari score ≥11) and very severe diarrhea (Vesikari score ≥15), and among G and P strains with at least 40 specimens. RESULTS: A total of 776 children were enrolled. For children <1 year and ≥1 year of age with severe diarrhea, VE for 2 doses was 75% (95% confidence interval [CI], 46%-88%) and 53% (95% CI, 9%-76%), respectively. For children <1 year and ≥1 year of age with very severe diarrhea, VE for 2 doses was 80% (95% CI, 44%-93%) and 74% (95% CI, 35%-90%), respectively. Genotype-specific analysis demonstrated similar VE for the 4 most common G and P types (G3, G9, P[6] and P[8]). CONCLUSIONS: A monovalent rotavirus vaccine remains effective against a broad range of circulating strains as part of a routine immunization program >5 years after its introduction in Bolivia. Although VE appears to wane in children aged ≥1 year, it still provides significant protection, and does not wane against severe disease.

Impact of rotavirus vaccination on child mortality, morbidity, and rotavirus-related hospitalizations in Bolivia.

BACKGROUND: The public health impact of rotavirus vaccination in countries with high child mortality rates remains to be established. The RV1 rotavirus vaccine was introduced in Bolivia in August 2008. This study describes the trends in deaths, hospitalizations, and healthcare visits due to acute gastroenteritis (AGE) and in rotavirus-related hospitalizations, among children <5 years of age, during the pre- and post-vaccination periods. METHODS: Data were obtained from the National Health Information System to calculate vaccine coverage and AGE-related health indicators. Trend reductions in the main health indicators were examined using the pre-vaccine period as baseline. The effect of vaccination on the epidemiology of rotavirus-related AGE was assessed using data from the active surveillance hospitals. RESULTS: Compared with the 2001-2008 pre-vaccine baseline, the mean number of rotavirus-related hospitalizations was reduced by 40.8% (95% confidence interval (CI) 21.7-66.4%) among children <5years of age in the post-vaccine period (2009-2013). Reductions were most pronounced in children <1year of age, eligible for vaccination. The mean proportions of AGE-related deaths, AGE-related hospitalizations, and AGE-related healthcare visits during 2009-2014 were reduced by 52.5% (95% CI 47.4-56.3), 30.2% (95% CI 23.5-36.1), and 12.9% (95% CI 12.0-13.2), respectively. The greatest effect in reduction of AGE-related deaths was found during the months with seasonal peaks of rotavirus disease. Over the post-vaccine period, changes in rotavirus epidemiology were observed, manifested by variations in seasonality and by a shift in the mean age of those with rotavirus infection. CONCLUSIONS: The significant decrease in main AGE-related health indicators in children <5years of age after the introduction of rotavirus vaccine provides evidence of a substantial public health impact of rotavirus vaccination in Bolivia, as a measure for protecting children against AGE.