Estimation of the number of people affected by post COVID-19 condition in Switzerland in 2023: A mathematical model.

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 modelling.

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, cardiopulmonary). We explored different scenarios to account for the uncertainty in model parameters and report the mean value with full range of results.

Results: During October-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 six months.

Conclusions: At least 1% of the Swiss population are 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 on a high level also in the future.