In this edition of the Explained series, we find out what studies suggest about these silent carriers.
Remarks by WHO's technical lead Dr Maria Van Kerkhove led to confusion among health officials who had recommended that people must wear masks to prevent the spread of the coronavirus.
Dr Van Kerkhove said that coronavirus transmission by asymptomatic people is 'very rare'. She later clarified to the "misunderstandings" calling asymptomatic transmission a " big open question".
In this edition of the Explained series, we find out about asymptomatic transmission.