This has important implications for the interpretation of immunogenicity measurements made after the 4th month post-vaccination. In particular, the change point would imply that immunogenicity measurements made during the second slower period of antibody decay, for example at 6 months, are indicative of longer-term seroprotection levels. Our estimation of the duration of this initial period

of rapid decline should be interpreted with some caution as it is dependent on the number of observation points during the first year post-vaccination. We were able to rely in our analysis on BMS-387032 concentration measurements made at days 28, 56 and at 6 months but more observation points between 6 months and 1 year after vaccination would have helped refine this analysis. Apart from the number of available antibody measurements, our study had three main limitations. Firstly we used data collected in study conducted in adults in an area where JE does not circulate. Our estimates would therefore likely to be conservative if applied to populations living in areas where the virus is endemic. The study population for our analyses were mostly

flavivirus-negative at baseline (10% positive to flaviviruses and 5% positive to JE and dengue specifically) with limited natural exposure. In settings where exposure to JE is more common, natural boosting is likely to lead to higher antibody titres and longer-lasting seroprotection. Dolutegravir datasheet Another source of potential bias is the loss to follow-up by year 5 if the distribution of early antibody titres was different among those still present at year 5 versus those who were not. However, we

compared antibody titres observed at 6 months between these two sub-groups and found no difference (p = 0.51; Kruskal–Wallis test of centrality). Another limitation of our study is that the findings were restricted to adults. Our conclusions may not extend to a paediatric population; antibody persistence data in children and toddlers would help confirm our findings for younger age groups. Our analyses were based on data from a study described in a previous paper [11]. While Farnesyltransferase the overall conclusions on the long-term seroprotection concord, some of our findings differ from those reported in this paper. This can in fact be explained by differences in the methodological approach. They notably chose the Kaplan–Meier method as their primary statistical analysis and found that 87% of 90 subjects who did not receive a second dose of JE-CV and who were seroprotected at 6 months were still protected at 5 years. Unlike the Kaplan–Meier method, our analyses keeps under observation those subjects who miss one antibody test but return for a test in a later year. Our estimate of protection at year 5 was more optimistic at 93.5% amongst those seroprotected at 28 days. This is also reflected in our model-based estimate of 94.7% seroprotection at 5 years.