The number of confirmed global cases of COVID-19 has officially crossed the 1 million mark. At the time of writing, 51,485 people worldwide have died from the virus, a large proportion of them in Europe and China. Over 208,000 people have recovered from the condition.

The respiratory disease is caused by a new coronavirus, SARS-CoV-2, similar to the coronavirus responsible for severe acute respiratory syndrome (SARS). The SARS outbreak of 2002-2003 affected 26 countries, with more than 8,000 confirmed cases and 774 deaths. 

COVID-19's most common symptoms are loss of smell and taste, shortness of breath, a dry cough, and fever, but some people appear to be asymptomatic as they remain infectious. The virus is passed on through droplets in the air from someone who is infected, which can then contaminate people or surfaces. A recent study found that the virus remains active on certain surfaces for days, which is why experts recommend washing your hands if you've had to leave your home.

The disease was first reported in late-December in the Chinese city of Wuhan, but spread quickly and was declared a pandemic by the World Health Organization (WHO) in early March. The exact origin of the virus remains uncertain and there is as yet no vaccine or specific antiviral treatment for it, though many are in the early stages of being trialed.

So far, it appears elderly people and those of every age with underlying health conditions are more at risk of succumbing to the disease. This does not mean that young people are immune to it. Although they are less likely to show symptoms, they are just as capable of spreading the virus.

SARS-CoV-2 is highly damaging to the lungs. Recent CT scans of a patient with no underlying health conditions showed extensive damage to the alveoli, the region in the pulmonary tract where carbon dioxide is exchanged for oxygen in the bloodstream. However, it's currently unknown if damage caused by the virus is temporary or long term.

To curb the spread of the disease and to prevent health services from becoming overwhelmed, many countries have instituted preventative measures. The WHO has advised people to take precautions like washing hands, coughing into your elbow, and throwing tissues away immediately. Physical distancing is also key to curbing the spread of the virus.

It is estimated that one-third of humanity is currently under lockdown, with citizens only permitted to leave their homes for essential goods, essential work, and exercise. The WHO is urging all countries to start mass testing so that people who test positive can self-isolate and stop spreading the disease further. This has already proven successful in Iceland and South Korea.