A new coronavirus appeared in Wuhan, China, at the start of December, and it has since infected millions of people all over the world. In March, the World Health Organization declared that the virus was a pandemic.

Coronaviruses are common in many types of animals and can sometimes jump to humans. In this case, the virus probably originally came from a bat. Two other coronaviruses have infected humans, causing outbreaks of SARS and MERS in 2002 and 2012, respectively.

The illness caused by the new coronavirus, COVID-19, appears to cause fever, cough, and difficulty breathing. Other symptoms include loss of taste and smell and gastrointestinal problems. Some people never display symptoms but could still infect others. The illness appears to be severe in around a quarter of COVID-19 patients, and thousands of people have died from the disease in the US and around the world.

Public health officials are still trying to control raging outbreaks in many countries, and scientists are searching for treatments. As that work continues, businesses are shuttered, hospitals are struggling, and millions of people are staying quarantined for their safety and the safety of others.

Follow all of the updates on this evolving story here.