Note: the following information is from a lecture by Dr Anna Seale of the London School of Tropical Health and Medicine
Let's begin with a definition of the key terms.
Coronavirus is not new. It is a large family of viruses, first identified in the 1960s, which get their name from the crown-like spikes seen on their surface with electron microscopy.
They can cause very mild symptoms like a common cold, or in some cases, they can cause severe disease.
There are many coronaviruses in animals and some in humans.
Occasionally a virus infecting animals may evolve to infect humans. The virus causing the disease Severe Acute Respiratory Syndrome, SARS, in 2002 came from civet cats and had a fatality rate of 10% and the virus causing Middle Eastern Respiratory Syndrome, MERS, in 2012 came from dromedary camels and had a fatality rate of 33%.
The new type of coronavirus is called SARS-CoV-2 which causes the disease named COVID-19 and so far has a fatality rate of around 2%.
Cases were first reported in December 2019 in Wuhan, a city of 11 million, the capital of Hubei Province, China.
Many early cases were associated with the Huanan Seafood Wholesale Market in Wuhan though it has yet to be proven if this was the site of the emergence. It is also not yet clear which animal the new coronavirus is associated with, although some data suggests it is similar to those found in bats.
Coronaviruses affect the breathing passages, or respiratory tract. Symptoms can be mild like the common cold, including a runny nose and cough or they can be more severe and can cause difficulty in breathing. Not everyone infected with the SARS-CoV-2 virus has symptoms.
Other common symptoms are fever, cough, and feeling tired.
Some people become seriously ill but this seems more likely in the elderly and those with other health problems.
Respiratory viruses are usually transmitted through either droplets, aerosols, or contact.
Droplets are larger particles that travel less than a metre while aerosols are smaller particles that can travel further. Contact is usually from droplets landing on objects which are touched by another person who then touches their eyes, nose, or mouth.
The main way the virus causing COVID-19 seems to spread is via droplets. This is why health experts are recommending washing hands, maintaining distance from those coughing or sneezing, and not touching your hands or mouth.
These actions will prevent infection by preventing droplet or contact transmission.
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