Transition to endemic: Two-year SARS-CoV-2 surveillance follow-up of the ELISA cohort.

The COVID-19 pandemic remains a significant challenge to global health despite the application of vaccines to approximately 70% of the world's population [1]. Unresolved questions include the duration of immunity after infection and vaccination, the effectiveness of vaccines against new virus variants, the relationship between antibody levels and immunity, re-infection risk, and long-term consequences of infection, including Long- and Post-COVID-syndrome. Thus, there is an unmet need for long-term, prospective epidemiological studies addressing these issues in the post-vaccination era.