Overview of 2019 novel coronavirus (2019-nCoV)

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• 作者：bmjchina
• 日期：2020-01-23
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Introduction

The 2019 novel coronavirus (2019-nCoV), also known as nCoV or Wuhan novel coronavirus (there is no internationally agreed name as yet), has been identified during an outbreak of pneumonia in Wuhan City, Hubei Province, China. Investigations to learn more about the novel coronavirus, its origin, and how it affects humans are ongoing, and the situation is evolving rapidly.
Preliminary investigations suggested that the virus did not transmit readily between people; however, based on the latest information available, the World Health Organization (WHO) has said that there is evidence of limited human-to-human transmission. China’s National Health Commission has confirmed cases of human transmission, with health care workers currently among the infected.[1]
There are increasing concerns about the virus spreading with hundreds of millions of people travelling across China for the Lunar New Year this week. WHO will convene an emergency committee to ascertain whether the outbreak constitutes a public health emergency of international concern on the 22nd January, 2020. Currently, the risk to other countries is thought to be low; however, the situation is under constant review.

Epidemiology

On the 31st December, 2019, WHO was informed of 44 cases of pneumonia of unknown microbial aetiology associated with Wuhan City, Hubei Province, China. Most of the patients in the outbreak reported a link to a large seafood and live animal market (Huanan South China Seafood Market), which has been closed since the 1st January, 2020 for environmental sanitation and disinfection.[2]
On the 9th January 2020, WHO announced that a novel coronavirus that has not previously been identified in humans had been detected in samples taken from patients in Wuhan City. Laboratory tests ruled out SARS-CoV, MERS-CoV, influenza, avian influenza, and other common respiratory pathogens.[3]
As of the 20th January, WHO have confirmed 282 cases with 12 patients in critical condition. The majority of cases are in Wuhan City; however, cases have also been confirmed in Beijing, Shanghai, and the Guangdong province. Six deaths have been reported, all from Wuhan City.[4] Travel-related cases have been reported in Thailand, Japan, the Republic of Korea, Taiwan, Macau, and the US. The first travel-related case in the US was confirmed on the 21st January in Washington state. The patient recently returned from Wuhan City.[5] The situation is evolving rapidly and the latest case counts may be higher. News reports put the case count at 461 with 9 deaths as of the 22nd January.

Etiology

Coronaviruses are a large family of viruses, some of which cause illness in people (e.g., common cold, severe acute respiratory syndrome [SARS], Middle East respiratory syndrome [MERS]), and others that circulate among animals such as bats and camels. Rarely, animal coronaviruses can spread to humans, and then spread between people as was the case with MERS and SARS.
Most, but not all, patients in the outbreak in Wuhan City have reported a link to Huanan South China Seafood Market, which suggests a zoonotic origin of the virus. The animal reservoir is unknown at this point.
The full genome of the virus has been published in GenBank. GenBank

Diagnosis

Diagnosis should be suspected in patients with signs and symptoms of pneumonia who report a travel history to an affected location, or who report direct contact with a person with confirmed or suspected novel coronavirus infection in the 14 days prior to symptom onset. Suspected cases should be reported to the relevant local health authorities.
Fever and cough are the most common presenting symptoms. Some patients may also have difficulty breathing. Chest x-rays may show bilateral lung infiltrates.[3] Other symptoms of coronavirus infection include shortness of breath, breathing difficulties, and other respiratory symptoms, as well as sore throat, nasal congestion, malaise, headache, and myalgia. Patients may also present with sepsis or septic shock.
WHO have published an interim case definition for human infection with novel coronavirus. WHO: surveillance case definitions for human infection with novel coronavirus (nCoV) 
WHO have published interim guidance for laboratory testing to confirm diagnosis. WHO: laboratory testing for 2019 novel coronavirus (2019-nCoV) in suspected human cases 

Management

There is no evidence to recommend any specific treatment for suspected or confirmed novel coronavirus infection. Management should follow recommendations for other severe acute respiratory infections and include appropriate infection control measures (standard, droplet, airborne, and contact precautions; eye protection), managing sepsis if present, supportive therapies (e.g., oxygen, fluid management, empirical antibiotics, intubation, mechanical ventilation), and close monitoring.
WHO have published interim guidance on the management of patients with novel coronavirus infection. WHO: clinical management of severe acute respiratory infection when novel coronavirus (nCoV) infection is suspected 
WHO have published interim guidance on the management of patients with mild infection at home and contacts. WHO: home care for patients with suspected novel coronavirus (nCoV) infection presenting with mild symptoms and management of contacts 

Prevention

There is no vaccine available.
WHO have published interim guidance on infection control and prevention during health care. WHO: infection prevention and control during health care when novel coronavirus (nCoV) infection is suspected 
WHO does not currently recommend any trade or travel restrictions on China. They advise international travellers to practice usual precautions while travelling in or from affected areas, including: avoiding close contact with people suffering acute respiratory infections; frequent hand washing, especially after contact with people who are ill or their environment; practicing appropriate cough etiquette; and avoiding close contact with live or dead farm or wild animals. WHO advice for international travel and trade in relation to the outbreak of pneumonia caused by a new coronavirus in China
The US Centers for Disease Control and Prevention (CDC) recommend that travellers practice usual precautions. CDC: travelers' health - novel coronavirus in China 
A number of countries, including Singapore, Hong Kong, Thailand, Malaysia, South Korea, Australia, and the US (San Francisco, New York, Los Angeles) are actively screening incoming travellers from China for signs and symptoms of infection.

Other guidelines

CDC: interim guidance for healthcare professionals 
CDC: infection control 
CDC: implementing home care 
CDC: guidelines for clinical specimens
Public Health England: Wuhan novel coronavirus (WN-CoV) 

Resources

BMJ: news
WHO: coronavirus
CDC: 2019 novel coronavirus (2019-nCoV)
Public Health England: Wuhan novel coronavirus (WN-CoV)

Related conditions

Middle East respiratory syndrome (MERS)
An acute viral respiratory tract infection caused by the novel betacoronavirus MERS-CoV, first identified in Saudi Arabia in 2012. Cases have been limited to the Arabian Peninsula and its surrounding countries, and to travellers from the Middle East or their contacts.

Severe acute respiratory syndrome (SARS)
A viral pneumonia that rapidly progresses to respiratory failure caused by the novel SARS-CoV coronavirus. There have been no reported cases since 2004.

Avian influenza A (H5N1) virus infection
Highly pathogenic avian influenza (HPAI) A H5N1 virus originates in poultry and wild birds can be transmitted to humans, with rare cases of infection transmitted between humans.

Avian influenza A (H7N9) virus infection
Geographically focused in China and associated with exposure to infected poultry. Five annual epidemic waves of human cases occurred from 2013 to 2017. Case clusters of limited human-to-human transmission have been described, but there is no evidence of sustained transmission.

Influenza infection
Acute respiratory tract infection typically caused by seasonal influenza A or B virus. The virus is transmitted by inhalation of infected respiratory secretions that have been aerosolised through coughing, sneezing, or talking.

Community-acquired pneumonia
Pneumonia acquired outside hospital or healthcare facilities. Clinical diagnosis is based on a group of signs and symptoms related to lower respiratory tract infection with presence of fever, cough, expectoration, chest pain, dyspnoea, and signs of invasion of the alveolar space.

Atypical pneumonia
Atypical bacterial pneumonia is caused by atypical organisms that are not detectable on Gram stain and cannot be cultured using standard methods.

Acute respiratory distress syndrome
Non-cardiogenic pulmonary oedema and diffuse lung inflammation syndrome that often complicates critical illness. Possible complication of novel coronavirus infection.

Sepsis
Life-threatening organ dysfunction caused by a dysregulated host response to an infection. Possible complication of novel coronavirus infection.

Shock
Life-threatening failure of adequate oxygen delivery to the tissues and may be due to decreased blood perfusion of tissues, inadequate blood oxygen saturation, or increased oxygen demand from the tissues that results in decreased end-organ oxygenation and dysfunction. Possible complication of novel coronavirus infection.

Contributors
Authors: Editorial Team