Epidemiology: Detection of SARS-CoV-2 in patients with influenza-like illness in Wuhan in early January

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detected in nine out of 640 re-analysed throat swabs collected from 6 October 2019 to 21 January 2020 from patients in Wuhan, China, who had influenza-like illness. These findings, reported in Nature Microbiology, suggest that community transmission of SARS-CoV-2 was established in Wuhan in early January.

Coronavirus disease 2019 (COVID-19) is caused by SARS-CoV-2. COVID-19 was first reported in Wuhan in late December 2019. By 23 February 2020, 60% of the 77,000 Chinese cases of SARS-CoV-2 infection were reported in Wuhan. The rapid increase of reported cases suggests that community transmission of SARS-CoV-2 was established in Wuhan and nearby regions no later than the end of January.

Man-Qing Liu and colleagues retrospectively investigated the presence of SARS-CoV-2 among local patients with influenza-like illness ― characterized by a sudden-onset fever over 38 °C and a cough or sore throat ― in Wuhan. The authors re-examined 640 throat swabs collected from patients during a 16-week period, which coincided with the winter peak of influenza and other respiratory illnesses. The samples were part of an influenza surveillance program. The patients in this cohort, from two national influenza sentinel hospitals in Wuhan, comprised 315 males and 325 females ranging from 9 months to 87 years of age.

The authors found that nine of the re-analysed swabs tested positive for SARS-CoV-2 RNA. These nine patients came from different districts of metropolitan Wuhan and surrounding areas, which provides evidence of community transmission in this area in early January 2020. This work adds information for understanding the early stage of the current pandemic.