Description of the COVID 2.0 survey in the NAKO and first results

INTRODUCTION: The COVID-19 pandemic had a huge impact on society and raised attention to the challenges related to infectious diseases. While a lot of research was initiated during the pandemic, the recruitment of participants in most instances started at the time point of infection. In contrast, the German National Cohort (NAKO Gesundheitsstudie) has the ability to study pre-existing risk factors. In order to obtain information about SARS-CoV-2 infections and the following sequelae a dedicated data collection was conducted. METHODS: An online survey was conducted in the NAKO between September 2022 and February 2023. Invitation via e-mail was followed by two reminders sent to all NAKO study participants who provided e-mail addresses. The questionnaire was implemented in LimeSurvey and included the following topics: current health status including mental health measurements, restrictions of health services during the pandemic, other collateral effects of the pandemic, reported infections with SARS-CoV-2 and symptoms of acute infection, 4-12 weeks, 12 or more weeks, and one year after infection as well as vaccination status. RESULTS: Of 150766 invited NAKO participants, 110362 responded to the second COVID-19 questionnaire. Respondents in 60% reported at least one SARS-CoV-2 infection, 59453 reported one, 6061 two, and 414 three or more infections. The time points of infections followed the general incidence in the German population and thus infections could be mapped to specific variants based on periods of dominance. Of those who reported an infection with SARS-CoV-2, 42% reported symptoms 4 to 12 weeks after infection (ongoing COVID-19), 35% reported symptoms 12 or more weeks after infection (Post-COVID-19), and 37% one year after infection. CONCLUSIONS: Combined with existing biosamples and measurements prior to infection, NAKO offers an excellent opportunity to study risk factors for infection and post-infection syndromes.