According to the World Health Organization, two employees at the Chinese Institute of Virology in Beijing contracted the SARS coronavirus in April 2004 independently, while studying the virus. The lab workers then spread the disease to seven others, resulting in one fatality.
The Beijing facility had been studying active and inactive variations of the SARS virus, and WHO noted "concern" over the incident, which occurred a year after the 2003 SARS outbreak. No known transmission of the SARS virus has occurred since 2004.