Description: Several studies have shown that individuals born during the 1957/58 influenza pandemic (H2N2) and 1969/70 (H3N2) have a higher risk of severe illness or death from the 2009 H1N1pdm09 pandemic compared to surrounding birth cohorts. The very first exposure to influenza viruses, including in-utero exposure, can weaken immune responses to various strains later in life, increasing the risk of severe infections in adulthood - an effect known as antigenic imprinting. Studies have demonstrated that early-life exposure to the influenza A virus impacts susceptibility to specific subtypes, as was also shown for the 2009 H1N1pdm09 pandemic. Additionally, increased morbidity and mortality from respiratory, cardiovascular, and cerebrovascular diseases have been observed during and after influenza pandemics and seasonal outbreaks.

A Master's thesis topic is available to investigate the effects of antigenic imprinting.
The aim of this thesis is to investigate birth cohort effects on hospitalisation in Switzerland. While most studies focus solely on age effects, this study aims to analyse the impact of birth cohorts, as this is also crucial for understanding the complex effects of influenza infections and the effect of antigenic imprinting.
Swiss hospital statistics will be used to analyse birth cohort effects on hospitalization rates for influenza and subsequent diseases during and shortly after the 2009 pandemic and for following H1N1pdm09 seasons. Since this data is only available in 5-year age groups, it first needs to be disaggregated into 1-year age groups before being analysed using generalized additive models or age-period-cohort (APC) models to identify birth cohorts with an elevated hospitalization risk. In addition, it is being investigated whether there is a cohort effect on the length and frequency of hospitalisation.

Contact: katarina.matthes@iem.uzh.ch