But one year on, with more than 81 million reported infections and 1.7 million deaths around the world, there's still a lot we don't know about Covid-19. Covid-19 is a coronavirus, a type of virus that is responsible for everything from the common cold, to SARS. Why it affects some people more than othersWhen Covid-19 was first identified, it was seen as a respiratory illness. We now know that even those who recover from Covid-19 can experience long lasting effects, including anxiety, brain damage and chronic fatigue. But scientists don't know how long these effects from Covid-19 last -- and they can't really explain why it is that some people suffer more than others.

Source: CNN December 29, 2020 00:45 UTC