So far as we know, up until this century the worst a coronavirus could do to people was to deliver the common cold, annoying but hardly deadly.
But three times so far in the last 20 years, novel coronaviruses have emerged that could potentially cause a pandemic—SARS (severe acute respiratory syndrome) in 2003, MERS (Middle East respiratory syndrome) in 2012, and now 2019-nCoV from Wuhan.
From what we understand, the virus originated from a Wuhan wet market, where live animals that would never normally meet in the wild live side by side, facilitating a species to species mutation.
The first known cases were not immediately linked to the market, and remained undetected amongst the usual day to day similar chest infections and symptoms of common colds and flu that are usually prevalent at this time of the year.
Slowly it increased its capacity to spread from human to human. As happened with SARS, it’s believed the new corona may be mutating along the way, gradually becoming more virulent.
The coronavirus physically, is quite a large virus in relative terms, at 125 nanometres with a surface of spike projections, it is considered too big to survive or stay suspended in the air for hours or travel more than just a few feet (which is something to be thankful for.)
This also reinforces how important it is to not touch your face after touching common objects, (buttons in a lift, door handles etc.) and wash your hands regularly.
Like SARS and MERS, the new coronavirus causes pneumonia, the infection of one or both lungs. It can potentially take about a week before an infected person feels sick enough to seek medical care.
After a slow start, the disease progresses rapidly during the second week, in a similar fashion to SARS. Hypoxemia caused by increasing lung injury leads to difficulty breathing and the need for oxygen therapy.
ARDS (acute respiratory distress syndrome) is a common complication.
Between 25 and 32 percent of cases are admitted to the intensive care unit (ICU) for mechanical ventilation.
Other complications include septic shock, acute kidney injury, and virus-induced cardiac injury.
It is then possible for the extensive lung damage to also set the lungs up for secondary bacterial pneumonia, which occurs in 10 percent of ICU admissions.
(This is believed to be the case for the Spanish flu of 1918, which killed 50 million people; the fatalities attributed to the viral influenza may be more because of the bacterial pneumonia.)
Infection by SARS and MERS lead to severe pneumonitis, ARDS, and respiratory failure, in all probability because of an exaggerated inflammatory reaction.
One puzzling aspect so far is the thankful lack of child victims. Usually, children, with less developed immune systems than adults, come down with one illness after another. Yet few children have yet been reported with coronavirus symptoms.
A similar pattern of benign disease in children, with increasing severity and mortality with age, was seen in SARS and MERS. SARS had a mortality rate averaging 10 percent. Yet no children, and just 1 percent of youths under 24, died, while those older than 50 had a 65 percent risk of dying.
Because there is no rapid diagnostic test, screening has focused on whether people have a fever, quickly overwhelming medical facilities until more time-consuming laboratory tests can be performed.
This is why the Hainan CDC has asked people with mild symptoms to first rest and treat their symptoms at home.
Related article: Jan 27th, ongoing updates on the coronavirus in Hainan