Department of Ecology and Evolutionary Biology, University of Chicago, Chicago, United States.
Center for Clinical Epidemiology and Population Health, Marshfield Clinic Research Institute, Marshfield, United States.
Elife. 2020 Jul 7;9:e50060. doi: 10.7554/eLife.50060.
Seasonal variation in the age distribution of influenza A cases suggests that factors other than age shape susceptibility to medically attended infection. We ask whether these differences can be partly explained by protection conferred by childhood influenza infection, which has lasting impacts on immune responses to influenza and protection against new influenza A subtypes (phenomena known as original antigenic sin and immune imprinting). Fitting a statistical model to data from studies of influenza vaccine effectiveness (VE), we find that primary infection appears to reduce the risk of medically attended infection with that subtype throughout life. This effect is stronger for H1N1 compared to H3N2. Additionally, we find evidence that VE varies with both age and birth year, suggesting that VE is sensitive to early exposures. Our findings may improve estimates of age-specific risk and VE in similarly vaccinated populations and thus improve forecasting and vaccination strategies to combat seasonal influenza.
季节性流感病例年龄分布的变化表明，除年龄因素外，还有其他因素影响着有医疗记录的感染易感性。我们想知道，这些差异是否可以部分归因于儿童期流感感染所带来的保护，这种保护对流感的免疫反应和预防新的甲型流感亚型（被称为原始抗原性和免疫印记的现象）产生持久影响。通过对流感疫苗有效性（VE）研究数据拟合统计模型，我们发现原发性感染似乎会降低一生中该亚型有医疗记录感染的风险。与 H3N2 相比，这种影响在 H1N1 中更强。此外，我们还发现 VE 随年龄和出生年份而变化的证据，这表明 VE 对早期暴露敏感。我们的研究结果可能会改进类似接种人群中特定年龄风险和 VE 的估计，从而改善季节性流感的预测和疫苗接种策略。
