Nosocomial outbreaks of influenza-like illness (ILI) or influenza are reported regularly.^1-3 Patients and health care workers (HCWs) may become infected themselves and, in turn, be sources of infection for others. Attack rates greater than 60% have been found in nursing homes during seasonal epidemics, with 10% lethality from influenza-related complications.⁴ The incidence rates in short-stay units are less well known. Seasonal influenza remains a frequent cause of hospitalization, and it was observed that the hospitalization rate increased during the influenza A/H1N1 pandemic.^5-7 In the United States, the community attack rates of seasonal influenza ranged from 10% to 20% by population groups and the hospitalization rate from 20 to 1000 per 100 000 inhabitants.⁸ Therefore, the risk of the virus spreading in health care settings is a major concern, especially in the elderly and individuals with immunosuppression or severe chronic disease.

A reliable diagnostic assay is crucial to early detect new COVID-19 cases and limit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. Since the onset of the COVID-19 pandemic, the World Health Organization has published several diagnostic molecular approaches developed by referral laboratories, including Charité (Germany), HKU (Hong Kong), China CDC (China), US CDC (United States), and Institut Pasteur, Paris (France). We aimed to compare the sensitivity and specificity of these different RT-PCR assays using SARS-CoV-2 cell culture supernatants and clinical respiratory samples. Overall, the different RT-PCR assays performed well for SARS-CoV-2 detection and were all specific except the N Charité (Germany), and N2 US CDC (United States) assays. RdRp Institut Pasteur (IP2, IP4), N China CDC, and N1 US CDC were found to be the most sensitive assays. The data presented herein are of prime importance to facilitate the equipment choice of diagnostic laboratories, as well as for the development of marketed tests.