Asymptomatic COVID-19 among university students during the low-risk transmission period

Based on the transmission indicators in 2023 and level of herd immunity, it is expected that there are still asymptomatic cases of COVID-19 in the population. The purpose of this study is to evaluate the prevalence and factors associated with asymptomatic SARS-CoV-2 infection during the low-intensity transmission period.

A cross-sectional study was conducted from February 20 to April 30, 2023 among students at the University of Belgrade. Data were collected through face-to-face interviews using a structured questionnaire. Students who visited the Student Health Center for health checks were invited to participate. Two nasopharyngeal swabs were collected, which were tested on-site using the SARS-CoV-2 rapid antigen test and RT-PCR in the laboratory.

Out of 1,307 university students enrolled in the study, 28 tested positive for SARS-CoV-2 on RT-PCR, resulting in a prevalence of asymptomatic SARS-CoV-2 cases of 2.1%. Based on the adjusted Firth's logistic regression model, independent factors associated with developing asymptomatic SARS-CoV-2 infection were: being male (odds ratio [OR] = 0.26, 95% confidence interval [CI] 0.12-0.55), living with people older than 65 years (OR = 1.90, 95% CI 1.03-3.16), bedtime until 10 pm (OR = 0.36, 95% CI 0.15-0.96), attending celebrations/parties (OR = 2.32, 95% CI 1.06-5.40), and having contact with a person who had a respiratory infection in the last 14 days (OR = 8.09, 95% CI 1.96-26.02).

The prevalence of asymptomatic infection in the university student population is around 2% during the low-risk transmission period. Despite the low prevalence of COVID-19, surveillance of COVID-19 should still continue in the future.