The clinical forms of this disease range from mild to very severe symptoms: pneumonia, a temperature and respiratory symptoms are the most common.
Other symptoms of the viral infection include a sore throat, aches and pains, or difficulty breathing. In some cases there may be nasal secretion, nausea and diarrhea.
The recently discovered outbreak of coronavirus starts mainly with nasal secretions or drops of saliva, once an infected individual sneezes or coughs. The estimated incubation time is 2 weeks. Due to the high rate of SARS-CoV-2 infection, the detection of asymptomatic positive patients is ,probably one of the key factors for controlling the outbreak.
The coronaviruses (CoV) are RNA, enveloped viruses, with a large genome (29.9 kb), of which the β-CoV and α-CoV are able to infect mammals.
The viruses belonging to the Coronaviridae family contain a higher abundance of the membrane protein (M) abundant among other proteins, that is, the peak glycoprotein (S), the nucleocapsid protein (N) and an envelope protein (E). The spike glycoprotein (S) is one of the targets of the T-cell response in the immune system. The S protein also facilitates the fusion of the viral envelope to the receptor ACE2 and the entrance of the virus in the target cell. The ACE2 receptors are present in the cells of the arteries, veins, smooth muscles, small intestine, lung alveoli, hair follicles, cardiac myofibroblasts, skin, brain and kidney. Consequently, the SARS-CoV-2 can potentially infect these tissues.
In December 2019, certain individuals working or living in the vicinity of the Huanan seafood market in Wuhan, in the province of Hubei, China, developed pneumonia of unknown cause.
Massive sequencing analysis of the respiratory samples revealed a new coronavirus, initially known as 2019 new coronavirus (2019-nCoV) and subsequently renamed as SARS-CoV-2.
On 11 March 2020, the WHO declared the disease a pandemic, due to the high number of individuals infected and the rapid spread of the disease around the world.