Rapid Risk Assessment: Cluster of pneumonia cases caused by a novel coronavirus, Wuhan, China, 2020

Risk assessment

European Centre for Disease Prevention and Control. Cluster of pneumonia cases caused by a novel coronavirus, Wuhan, China, 2020.

The likelihood of importation of cases of novel coronavirus (2019-nCoV) to the EU is considered to be low, but cannot be excluded in the current situation.This document presents disease background, risk assessment and options for response.

Executive summary

A novel coronavirus (2019-nCoV) has been isolated and considered the causative agent of the cluster of 41 pneumonia cases in the area of Wuhan, Hubei province in China, and three travel-related cases in Thailand and Japan, arriving from Wuhan.

The majority of detected pneumonia cases reported having visited the Wuhan Huanan Seafood Wholesale Market recently before disease onset. Some cases did not report any exposure to this specific market, but to other food markets in Wuhan. For a few cases there was no direct connection with a food market. The Wuhan Huanan Seafood Wholesale Market has been closed and disinfected. However, there is no information available on restrictions at other food markets in Wuhan. If the sources of the infections are indeed certain animals sold in the market, other markets in the city may continue to pose a risk of infection. At the moment, there is no information on the source of infection or the transmission mode. The occurrence of a few cases having no history of contact with the implicated market or other any similar market suggests the possibility of the infection source being even more widely distributed.

As of 16 January 2020, there is no clear indication of sustained human-to-human transmission. The report of two small family clusters in Wuhan and the exposure history of the imported Japanese case (history of contact with a person with an acute, not laboratory confirmed, respiratory infection in Wuhan) suggest that person-to-person transmission may have occurred. In the absence of detailed information from the ongoing studies in China, it is impossible to quantify the potential of the 2019-nCoV for human-to-human transmission.

The clinical information on confirmed 2019-nCoV cases reported so far suggests a milder disease course than that observed in SARS-CoV and MERS-CoV cases. However, in the absence of results from ongoing epidemiological investigations, it is impossible to assess whether there are population groups at higher risk of severe illness.

Risk for travellers, importation and further spread in the EU

Three EU airports have direct flight connections to Wuhan and there are indirect flight connections to other EU hubs. The likelihood of EU/EEA travellers becoming infected while visiting any wet or live animal markets in Wuhan is considered to be moderate, as the source of infection is unknown and could still be active. The likelihood of infection for travellers visiting Wuhan, but not visiting these markets, is considered low, because so far there is no indication of virus circulation in the community.

Therefore, the likelihood of importation of cases of 2019-nCoV to the EU is considered to be low, but cannot be excluded in the current situation.

The upcoming Chinese New Year celebrations at the end of January 2020 will cause an increase in the volume of travel to/from China and within China, increasing the likelihood of possible cases arriving in the EU.

If a case is identified in the EU, rigorous infection prevention and control measures (IPC) should be applied. Current evidence that human-to-human transmission is limited indicates that the assessed likelihood of further spread in the community setting within the EU/EEA is very low, but the risk cannot be excluded.

Risk of nosocomial transmission, infection prevention and control

So far, there are no reported instances of disease transmission to healthcare workers/medical personnel in China, Japan and Thailand. Therefore, the likelihood of nosocomial transmission is considered very low, provided that appropriate IPC measures are applied [41].

Risk of transmission in airplane

There are no specific guidelines for assessing the risk of 2019-nCoV transmission during a flight. Assessment should be made on a case-by-case basis. As the current level of uncertainty regarding transmission of 2019-nCoV is high, comprehensive contact tracing of confirmed cases should be considered and if this is not possible, efforts should be made to at least trace passengers seated in the same row and passengers seated two rows in front or behind the index case. In addition, ECDC will shortly be publishing an updated guide on MERS-CoV infections during a flight.