It feels like an eternity ago, but the world only became aware of the coronavirus in December.
Despite incredible efforts by scientists around the world, there is still much we do not understand, and we are all now part of a planet-wide experiment trying to find answers.
Here are some of the big outstanding questions.
1. How many people have been infected.
It is one of the most basic questions, but also one of the most crucial.
There have been hundreds of thousands of confirmed cases around the world, but this is only a fraction of the total number of infections. And the figures are further confused by an unknown number of asymptomatic cases – people who have the virus but don’t feel ill. (Text and photo courtesy BBC)