2019 Coronavirus pandemic outbreak

The 2019-2021 Coronavirus pandemic outbreak of ME/CFS began with the 2019 SARS-CoV-2 viral outbreak, which was declared a pandemic in January 2020. SARS-CoV-2 caused most infected people to develop COVID-19, which then led to a substantial number of people developing Long COVID (long term COVID-19-like symptoms). A significant proportion of Long COVID patients was found to have developed ME/CFS, although it is uncertain what the likelihood of ME/CFS is after COVID-19 infection.

History
The new SARS-COV-2 virus was find to be very similar to the previous severe acute respiratory syndrome coronavirus that led to the 2003 Hong Kong outbreak of ME/CFS. The high degree of transmission and high rate of COVID-19 resulting from the new coronavirus led to the World Health Organization announcing that COVID-19 was a pandemic on March 11, 2020.

Outbreak announcement
In March 2021, while what became known as the coronavirus (COVID-19) pandemic was still ongoing, the US National Institute of Neurological Disorders and Stroke highlighted a group of cases of ME/CFS arising directly after COVID-19. The Open Medicine Foundation referred to the ME/CFS outbreak as a "potential second pandemic".