COVID-19 was the first coronavirus pandemic. The original Sars virus from 2003 and the Mers virus that created a health emergency in South Korea in 2015 were both coronaviruses, but fortunately failed to turn into pandemics in the way that COVID did.
Four years on from its appearance, Sars-CoV-2 (the virus that causes COVID) now seems to be making the transition to an endemic virus: one that circulates in humans all the time, at least somewhere in the world. As is common in respiratory viruses, it also seems to be developing a seasonal preference for the colder, wetter times of the year.
But Sars-CoV-2 isn’t alone. There are four other circulating coronaviruses, named OC43, NL63, HKU-1 and 229E. The consensus is that these viruses are also descendants of past pandemics and that Sars-CoV-2 is just the latest member of their club.
