You can’t switch on the news right now without hearing the word ‘coronavirus’. But coronaviruses are actually nothing new and most people will be infected with one at some point in their life. But don’t worry, most coronaviruses cause only moderate symptoms.
In fact, of the seven known coronaviruses that affect humans, four are endemic (found regularly) and rarely cause severe disease on their own. These four are called 229E, OC43, NL63, and HKU1. Coronaviruses 229E and OC43 usually result in the common cold most of us experience from time to time, particularly during the winter.
However, there are also three known coronaviruses that cause more severe symptoms: SARS-CoV, MERS-CoV and the one we are dealing with now, SARS-CoV-2. What SARS, MERS and the new coronavirus have in common is that they are more dangerous for people with underlying medical conditions. And while SARS and MERS have significantly higher case fatality rates than COVID-19, the latter is more infectious.
Finally, it is worth noting that there have been no new SARS cases for over a decade. However, MERS remains a public health concern, with a handful of cases cropping up every year.
Two of the biggest challenges with the current SARS-CoV-2 outbreak are that many people are asymptomatic and our lust for international travel and the ease with which we can do it have allowed the virus to spread rapidly around the globe.
[Related reading: Why COVID-19 hits some people harder than others]