Cohort study design for estimating the effectiveness of seasonal influenza vaccines in real time based on register data: The Finnish example.

Cohort study design for estimating the effectiveness of seasonal influenza vaccines in real time based on register data: The Finnish example. Scand J Public Health. 2018 Nov 02;:1403494818808635 Authors: Baum U, Auranen K, Kulathinal S, Syrjänen R, Nohynek H, Jokinen J Abstract This paper presents the principles of implementing register-based cohort studies as currently applied for real-time estimation of influenza vaccine effectiveness in Finland. All required information is retrieved from computerised national registers and deterministically linked via the unique personal identity code assigned to each Finnish resident. The study cohorts comprise large subpopulations eligible for a free seasonal influenza vaccination as part of the National Vaccination Programme. The primary outcome is laboratory-confirmed influenza. Each study subject is taken to be at risk of experiencing the outcome from the onset of the influenza season until the first of the following three events occurs: outcome, loss to follow up or end of season. Seasonal influenza vaccination is viewed as time-dependent exposure. Accordingly, each subject may contribute unvaccinated and vaccinated person-time during their time at risk. The vaccine effectiveness is estimated as one minus the influenza incidence rate ratio comparing the vaccinated with the unvaccinated within the study cohorts. Data collection in register-based research is an almost fully automated process....
Source: Scandinavian Journal of Public Health - Category: International Medicine & Public Health Authors: Tags: Scand J Public Health Source Type: research