Antibody testing during the coronavirus lockdown has come up several times during the government's daily briefings and has sparked discussions among medical experts and NHS staff.
The tests have been described by many scientists and even by Prime Minister Boris Johnson as "game-changing" - but what does that actually mean?
ITV News' Coronavirus: What You Need To Know podcast answers when will the antibody test be ready and just how accurate will it be?
Dr Emily Adams, Senior Lecturer at the Liverpool Tropical School of Medicine, speaks to ITV News Health Correspondent Emily Morgan and ITV News Science Editor Tom Clarke about what an antibody test is and how it could be ready in a "week or so".
She also tells ITV News about the rate of antibody response and despite being able to easily purchase an antibody test online, it might not have been validated thoroughly yet.
"It's really important not to put a bad test out there, Chris Whitty has reassuredly said that," Dr Adams said.
Coronavirus: Everything you need to know