COVID19 TALE

We don’t yet know how dangerous Covid-19 is, and we won’t know until more data comes in. The mortality rate seems to be around 2%. For comparison, seasonal flu typically has a mortality rate below 1% and is thought to cause about 400,000 deaths each year globally. Sars had a death rate of more than 10%.

Another key unknown, of which scientists should get a clearer idea in the coming months, is how contagious Covid-19 is. A crucial difference is that unlike flu, there is no vaccine for the new coronavirus, which means it is more difficult for vulnerable members of the population – elderly people or those with existing respiratory or immune problems – to protect themselves. Hand-washing and avoiding other people if you feel unwell are important. One sensible step is to get the flu vaccine, which will reduce the burden on health services if the outbreak turns into a wider epidemic.

Like other coronaviruses, it originated in animals and then migrated to humans. In this case it appears to have originated in the city of Wuhan in China. Many of those initially infected either worked or frequently shopped in the Huanan seafood wholesale market in the centre of the city, which also sold live and newly slaughtered animals. China’s national health commission confirmed human-to-human transmission of the virus in January.

New and troubling viruses usually originate in animal hosts. Ebola and flu are other examples, and severe acute respiratory syndrome (Sars) and Middle Eastern respiratory syndrome (Mers) are both caused by coronaviruses that came from animals. In 2002, Sars spread virtually unchecked to 37 countries, causing global panic, infecting more than 8,000 people and killing more than 750. Mers appears to be less easily passed from human to human, but has greater lethality, killing 35% of about 2,500 people who have been infected.

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