Novel coronavirus-infected pneumonia
Novel coronavirus-infected pneumonia (NCIP) is an emerging zoonotic illness caused by a hitherto unknown coronavirus, which has provisionally been called 2019 novel coronavirus or 2019-nCoV by the World Health Organization (WHO). The first cases were seen in the city of Wuhan, China in December 2019, and have been linked to the Huanan Seafood Wholesale Market 1,2,10. Person-to-person transmission can occur.
The infection was declared a Public Health Emergency of International Concern (PHEIC) on January 30th 2020 by the WHO 7.
As of February 10th 2020, over 40,500 cases of novel coronavirus-infected pneumonia have been identified worldwide, with the vast majority (~99%) in China, according to a Johns Hopkins online virus tracker 5.
On January 13th 2020, the first confirmed case outside China was diagnosed, a Chinese tourist in Thailand 10. On January 20th, the first infected person in the United States was confirmed to be a man in the State of Washington who had recently returned from a visit to Wuhan 9. The disease has now been diagnosed in 28 territories, including Macau and Hong Kong, in five continents 5,13.
The mortality rate is about 2-3% 2,5 with currently 910 confirmed deaths (February 10th, 2020) 5. Only two confirmed deaths have been outside mainland China, one in Hong Kong, and a second one in the Philippines 5.
A recent modelling study suggested that the true number of cases of infection is much higher than published official figures, being greater than 75,000 infected persons in Wuhan 8.
The R0 (basic reproduction number) of the novel coronavirus has been estimated as 2.2; i.e. each infected individual - on average - causes 2.2 new cases of the disease 12. The incubation period has been calculated to be 5.2 days on average 12.
The novel coronavirus primarily presents as pneumonia, however, its full spectrum of clinical effects remains to be determined 1,2. Symptoms are non-specific:
The recently identified 2019-nCoV is the confirmed cause of novel coronavirus-infected pneumonia. It is a member of the Betacoronavirus genus, one of the genera of the Coronaviridae family of viruses. Coronaviruses are enveloped single-stranded RNA viruses, that are found in humans, many other mammals and birds. These viruses are responsible for pulmonary, hepatic, CNS and intestinal disease.
The natural animal host of 2019-nCoV remains undetermined 11.
Hitherto, six coronaviruses have been known to be responsible for human diseases, two are zoonoses, the severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV), both of which may sometimes be fatal. The remaining four viruses are widespread in human society and cause mild coryzal illnesses.
The primary findings on chest radiograph and CT are those of pneumonia 3. 75% of cases have presented with bilateral pneumonia 6.
Treatment and prognosis
No specific treatment or vaccine exists for this emerging illness (as of February 2020). Therefore in the meantime, resources have been concentrated on public health measures, to prevent further interhuman transmission of the virus. This has required a multipronged approach and for individuals includes meticulous personal hygiene, fitted masks, and the avoidance of large crowds/crowded environments 11.
In healthcare facilities, concerted efforts are required to effect rapid diagnosis, quarantine infected cases and provide effective supportive therapies. This will encompass empirical treatments with antibiotics, antivirals, steroids and supportive measures. Mechanical ventilation and extracorporeal membrane oxygenation (ECMO) have also been used where clinically necessary.
Vaccines for the coronaviruses have been under development since the SARS outbreak, but none are yet available for human patients 11.