Prevalence of respiratory virus infections during a SARSCoV2 epidemic

Background: On 10 March 2020, the World Health Organization declared a global pandemic due to widespread infection of the novel coronavirus SARS-CoV-2 This epidemic struck while the winter epidemics of respiratory viruses were not yet finished In order to better understand the aetiologies of influenza-like syndromes in the COVID-19 period, we analysed the samples taken in a hospital screening centre in Paris, France at the very beginning of the epidemic Materials and methods: We collected nasopharyngeal swabs from persons attending the outpatient testing unit of Stantoine University Hospital in Paris from 28 February to 27 March 2020 Real-time polymerase chain reaction (RT-PCR) was performed for SARS-CoV-2 and for the most common respiratory pathogens Patient characteristics, symptoms at presentation and risk factors were collected Data were analysed for normality and descriptive statistics were presented as a number (%) for categorical variables and median (interquartile range [IQR]) for continuous variables Chi-square test was used for categorical variables Results: Overall, 707 patients sought medical care According to the former testing strategy 468 patients (66 2%) qualified for testing by RT-PCR and were included in final analysis The median (IQR) age was 37 (29 to 50) years and 139 patients (29 7%) were male The prevalence of SARS-CoV2 was 37 4% and 37 patients (7 9%) were positive for other pathogens, mainly influenza Two hundred and fifty six patients (54 7%) had negative results Symptoms such as anosmia, fever and headache were more frequently seen in patients with SARSCoV2 compared to other pathogens (respectively 26 3% vs 2 7%, p < 0 00001;78 9% vs 64 9%, p < 0 02;45 1% vs 29 7%, p < 0 002), while nasopharyngitis was more common in patients with other viruses (24 3% vs 10 39%, p < 0 003) Over the study period, the prevalence of respiratory viruses other than SARS-CoV2 decreased (Week 1: 26 4%, Week 2: 7 3%, Week 3: 1 8%) until it became zero on the fourth week (Table 1) Conclusions: Over the period of March 2020 seasonal respiratory viruses quickly disappeared while COVID-19 affected more than a third of people consulting for an influenza-like illness in a hospital screening centre in Paris The anosmia-fever-headache triad has been found much more frequently in association with SARS-CoV2 than with other respiratory viruses and could be a warning sign in case of a new epidemic