Since its discovery in 2019, SARS-CoV-2, the virus that causes covid-19, has been found in many variants. In September 2020, a variant labeled B.1.1.7 was isolated in the UK and quickly became the prevailing lineage worldwide. It is assumed to be around 50% more transmissible than other variants.
As we now know, some covid-19 patients develop acute respiratory failure which can be life threatening. They often require treatment with antipyretics, supplemental oxygen, or mechanical ventilation.