CDC is closely monitoring an outbreak of respiratory illness caused by a novel (new) coronavirus (termed “2019-nCoV”) that was first detected in Wuhan City, Hubei Province, China and which continues to expand. Chinese health officials have reported hundreds of infections with 2019-nCoV in China, including outside of Hubei Province. Infections with 2019-nCoV also are being reported in a growing number of countries internationally, including the United States, where the first and second 2019-nCoV infections were reported on January 21 and January 24, 2020, respectively, both in travelers returning from Wuhan.
Chinese health authorities were the first to post the full genome of the 2019-nCoV in GenBankexternal icon, the NIH genetic sequence database, and in the Global Initiative on Sharing All Influenza Data (GISAIDexternal icon) portal, an action which has facilitated detection of this virus. On January 24, 2020, CDC posted in GenBank the full genome of the 2019-nCoV virus detected in the first U.S. patient from Washington state. The virus genetic sequence from the patient in Washington is nearly identical to the sequences posted from China. The available sequences suggest a likely single, recent emergence from a virus related to bat coronaviruses and SARS-CoV. The available sequence information does not provide any information about severity of associated illness or transmissibility of the virus.
Coronaviruses are a large family of viruses, some causing illness in people and others that circulate among animals, including camels, cats and bats. Rarely, animal coronaviruses can evolve and infect people and then spread between people such as has been seen with MERS and SARS.
When person-to-person spread has occurred with MERS and SARS, it is thought to have happened via respiratory droplets produced when an infected person coughs or sneezes, similar to how influenza and other respiratory pathogens spread. Spread of MERS and SARS between people has generally occurred between close contacts. Past MERS and SARS outbreaks have been complex, requiring comprehensive public health responses.
Early on, many of the patients in the outbreak in Wuhan, China reportedly had some link to a large seafood and animal market, suggesting animal-to-person spread. However, a growing number of patients reportedly have not had exposure to animal markets, suggesting person-to-person spread is occurring. At this time, it’s unclear how easily or sustainably this virus is spreading between people.
Both MERS and SARS have been known to cause severe illness in people. The situation with regard to 2019-nCoV is still unclear. While severe illness, including illness resulting in a number of deaths has been reported in China, other patients have had milder illness and been discharged.
There are ongoing investigations to learn more. This is a rapidly evolving situation and information will be updated as it becomes available.