Human-to-human transmission of 2019-novel coronavirus (2019-nCoV)

Background: On December 31, 2019, an outbreak of 2019-nCoV in humans was reported in Wuhan, China. We analyzed data from field investigations and genetic sequencing to provide evidence of human-to-human transmission. Methods: A confirmed case of 2019-nCoV was defined if a suspected case was verified with positive of 2019-nCoV in throat swabs, nasal swabs, bronchoalveolar lavage fluid (BALF), or endotracheal aspirates by real-time reverse transcriptase polymerase chain reaction assay (RT-PCR) or genetic sequencing. Field investigations were conducted for each confirmed case. Clinical and demographic data of the confirmed cases were collected from their medical records. Exposure and travel histories were obtained by interviewing the confirmed cases. Results: Seventeen confirmed cases were identified from January 1 to 21, 2020 in Guangdong Province, China. Of them, two cases (11.8%) arisen locally without travel history to Wuhan or exposure history to wildlife market within 14 days prior to the onset of illness. These two cases were from two family cluster infections including 4 and 2 index cases, respectively. The whole viral genome from the two cases was exactly the same with their index cases, and presented a few unique single nucleotide variants (SNVs) which were predicted to cause one amino acid change in spike protein and Orf8 protein, respectively. Conclusions: This study identified two human-to-human transmitted cases of 2019-nCoV in Guangdong Province, China, which indicates that prevention strategies of cutting the person-to-person transmission of 2019-nCoV in households, hospitals and communities are urgently implemented.