Cent Eur J Public Health 2025, 33(3):170-175 | DOI: 10.21101/cejph.a8739

The importance of screening asymptomatic patients admitted to healthcare facilities during the COVID-19 pandemic

Petr Smejkal^{1, 2}, Filip Hrubý², Anna Horňáková¹

¹ Institute of Hygiene and Epidemiology, First Faculty of Medicine, Charles University, Prague, Czech Republic

² Institute for Clinical and Experimental Medicine, Prague, Czech Republic

Objectives: Screening of asymptomatic patients upon hospital admission became a key strategy to prevent nosocomial transmission of SARS-CoV-2 during the COVID-19 pandemic, particularly in facilities treating immunocompromised patients. Rapid antigen tests (RATs) were widely used due to their speed, but their reliability in detecting potentially infectious individuals remained debated. In parallel, the role of immunosuppression, especially in solid organ transplant (SOT) recipients, as a risk factor for asymptomatic positivity and prolonged viral shedding raised additional concerns. The aim of the study was to evaluate the diagnostic performance of rapid antigen testing compared to RT-PCR in asymptomatic patients admitted to a high-risk hospital, and the difference in SARS-CoV-2 PCR positivity between asymptomatic patients with and without a history of solid organ transplantation.

Methods: We retrospectively analysed 17,086 paired RAT and RT-PCR tests collected from 11,858 asymptomatic patients admitted to a tertiary care hospital between October 2020 and October 2022. Viral load was assessed via PCR cycle threshold (Ct) values. The sensitivity and specificity of RATs were calculated using PCR as the reference (Ct < 28).

Results: RATs showed a sensitivity of 83.5% and a specificity of 99.3% in detecting patients with high viral loads (Ct < 28). False negatives occurred predominantly in cases with low viral loads (Ct ≥ 28). SARS-CoV-2 PCR positivity was significantly higher in SOT patients (5.4%) than in non-transplant patients (3.2%) (p < 0.001), a difference that was consistent across viral variants.

Conclusions: RATs reliably identified the majority of asymptomatic patients with high viral loads who pose a risk of in-hospital transmission. SOT recipients represent a high-risk subgroup for asymptomatic SARS-CoV-2 carriage, underscoring the importance of rigorous admission screening protocols in specialized healthcare settings.

Keywords: COVID-19, SARS-CoV-2, antigen test, RT-PCR, transplant patients, asymptomatic infection, hospital screening, cycle threshold value

Received: July 25, 2025; Revised: September 27, 2025; Accepted: September 27, 2025; Published: September 30, 2025  Show citation