Decoding the virus – what we know about Sars-CoV-2 a year on

An illustration showing a coronavirus particle

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Scientists have never learnt so much about a pathogen in such a short time

In December 2019, an unusual respiratory illness emerged in Wuhan in China, with initial cases linked to a ‘wet market’ selling seafood and wild animals. Now, over a year on with more than 99 million confirmed cases and nearly 2 million deaths worldwide, the Covid-19 pandemic is the worst global public-health crisis since the 1918 Spanish Flu. As it continues to disrupt our lives, many questions still remain unanswered about Sars-CoV-2 – the virus behind the disease. We don’t know exactly why it drastically affects some people more than others, for example, or how long immunity might keep it at bay.