COVID-19 cases worldwide as of April 21, 2021, by country

As of April 21, 2021, the outbreak of the coronavirus disease (COVID-19) had been confirmed in over 210 countries and territories. The virus had infected almost 144 million people worldwide, and the number of deaths had reached three million. The most severely affected countries include the U.S., Brazil, and India.

COVID-19: background information

COVID-19 is a novel coronavirus that had not previously been identified in humans. The first case was detected in the Hubei province of China at the end of December 2019. The virus is highly transmissible, and thousands of new cases are being reported around the world each day. Coughing and sneezing are believed to be the most common forms of transmission, which is similar to the outbreak of the SARS coronavirus that began in 2002 and was thought to have spread via cough and sneeze droplets expelled into the air by infected persons.

Naming the coronavirus disease

Coronaviruses are a group of viruses that can be transmitted between animals and people, causing illnesses that may range from the common cold to more severe respiratory syndromes. In February 2020, the International Committee on Taxonomy of Viruses and the World Health Organization announced official names for both the virus and the disease it causes: SARS-CoV-2 and COVID-19, respectively. The name of the disease is derived from the words corona, virus, and disease, while the number 19 represents the year that it emerged.