Assessment of one-dose mumps-containing vaccine effectiveness on wild-type genotype F mumps viruses circulating in mainland China.

To clarify the protective effect of one-dose mumps-containing vaccines (MuCV) in mainland China, the antigenic variations of HN gene and cross-neutralization capacities between MuCV and wild type genotype F MuVs were studied. In total, 70 HN gene sequences of genotype F MuV representative strains obtained from 2001 to 2015, two types of MuCV strains, 139 pairs of pre- and post-vaccination serum samples from infants receiving one dose of MuCV vaccination were analyzed. Genotype-specific amino acid variations were observed in the potential antigenic epitopes between MuCV and wild-type genotype F MuVs circulating in mainland China. The mumps neutralization antibody titers induced by one-dose MuCV were found to be generally low. Moreover, significant differences in neutralization titers were observed between vaccine and wild-type strains. It could be concluded that one-dose MuCV had a cross-protective effect against the wild-type genotype F MuVs, but its effectiveness was limited, which might be caused by insufficient doses of MuCV vaccination and the genotype-specific antigenic differences between vaccine and wild-type MuVs as well. In addition, a poor linear correlation between mumps-specific IgG concentrations and neutralization titers was observed in this study, indicating the concentration of MuV-specific IgG could not fully reflect the neutralizing antibody titer in serum. Therefore, it is highly recommended to provide a second dose of MuCV to preschool children to increase MuV neutralizing antibody titers and use MuV cross-neutralization test as preferred tool for assessment of mumps-containing vaccine effectiveness on wild-type MuVs. This is the first report to assess the effectiveness of one-dose Chinese MuCV against wild-type genotype F MuVs, which would be benefit for the development of mumps vaccination strategy.

Human infection with avian influenza A H7N9 virus: an assessment of clinical severity.

BACKGROUND: Characterisation of the severity profile of human infections with influenza viruses of animal origin is a part of pandemic risk assessment, and an important part of the assessment of disease epidemiology. Our objective was to assess the clinical severity of human infections with avian influenza A H7N9 virus, which emerged in China in early 2013. METHODS: We obtained information about laboratory-confirmed cases of avian influenza A H7N9 virus infection reported as of May 28, 2013, from an integrated database built by the Chinese Center for Disease Control and Prevention. We estimated the risk of fatality, mechanical ventilation, and admission to the intensive care unit for patients who required hospital admission for medical reasons. We also used information about laboratory-confirmed cases detected through sentinel influenza-like illness surveillance to estimate the symptomatic case fatality risk. FINDINGS: Of 123 patients with laboratory-confirmed avian influenza A H7N9 virus infection who were admitted to hospital, 37 (30%) had died and 69 (56%) had recovered by May 28, 2013. After we accounted for incomplete data for 17 patients who were still in hospital, we estimated the fatality risk for all ages to be 36% (95% CI 26-45) on admission to hospital. Risks of mechanical ventilation or fatality (69%, 95% CI 60-77) and of admission to an intensive care unit, mechanical ventilation, or fatality (83%, 76-90) were high. With assumptions about coverage of the sentinel surveillance network and health-care-seeking behaviour for patients with influenza-like illness associated with influenza A H7N9 virus infection, and pro-rata extrapolation, we estimated that the symptomatic case fatality risk could be between 160 (63-460) and 2800 (1000-9400) per 100,000 symptomatic cases. INTERPRETATION: Human infections with avian influenza A H7N9 virus seem to be less serious than has been previously reported. Many mild cases might already have occurred. Continued vigilance and sustained intensive control efforts are needed to minimise the risk of human infection. FUNDING: Chinese Ministry of Science and Technology; Research Fund for the Control of Infectious Disease; Hong Kong University Grants Committee; China-US Collaborative Program on Emerging and Re-emerging Infectious Diseases; Harvard Center for Communicable Disease Dynamics; US National Institute of Allergy and Infectious Disease; and the US National Institutes of Health.