The new coronavirus (Covid-19) has spread to almost every country in the world since it first surfaced in China earlier this year. Over 10.9 million people are known to be infected and over 521,000 deaths have been recorded, including 44,131 in the UK.
What is a coronavirus?
Coronaviruses are a family of viruses that cause disease in animals. Seven, including the new virus, made the leap in humans, but most cause only cold-like symptoms.
Covid-19 is closely related to the severe acute respiratory syndrome (SARS) that swept the world from 2002 to 2003. That virus infected about 8,000 people and killed about 800 but soon ran out, largely because most of those infected were seriously ill so it was easier to control.
Another coronavirus is Middle Eastern Respiratory Syndrome (MERS), whose cases have occurred sporadically since its first appearance in 2012 – there have been around 2,500 cases and nearly 900 deaths.
Covid-19 differs from these other two coronaviruses in that the spectrum of the disease is broad, with approximately 80% of cases leading to a mild infection. There may also be many people who carry the disease and show no symptoms, making control even more difficult.
So far, about 20% of Covid-19 cases have been classified as “severe” and the current mortality rate varies between 0.7% and 3.4% depending on location and, above all, access to good hospital care.