Objectives: We aimed to estimate the prevalence and incidence of post COVID-19 condition (presence of symptoms related to a SARS-CoV-2 infection at least 3 months earlier) in Switzerland in 2023 using mathematical modeling.

Methods: We constructed a deterministic compartmental model of SARS-CoV-2 transmission, extended with a module to calculate incidence and prevalence of post COVID-19 condition stratified by symptom cluster (fatigue, neuropsychiatric, and cardiopulmonary). We explored different scenarios to account for the uncertainty in model parameters and reported the mean value with a full range of results.

Results: From October to December 2023, the model projected 61,300 (range across scenarios: 7900-195,000) new cases of post COVID-19 in Switzerland. The number of individuals with prevalent post COVID-19 remained stable during the year, decreasing minimally from 386,900 (87,500-930,600) in June to 380,800 (62,100-990,800) in December 2023. Neuropsychiatric disorders were the most common symptoms. About half of the individuals with post COVID-19 condition at the end of 2023 had been affected by the symptoms by more than 6 months.

Conclusions: At least 1% of the Swiss population is affected by the long-term consequences of COVID-19, and this proportion is likely to be multiple times higher. The prevalence is expected to remain at a high level also in the future.