The process of tracing contacts for Covid-19

Passengers fill up forms with their contact details for tracing, if necessary, upon arrival at the Murtala International Airport in Lagos, Nigeria. Contact tracing is standard procedure for viral epidemics. — AFP

It's painstaking, disruptive, and yet, potentially life-saving.

For every confirmed coronavirus case, health authorities face a race against time to identify everyone the patient has been in contact with and nip transmission in the bud.