A new HSE study aims to provide a national estimate of infection of Covid-19 in the population.
It'll ask over 5,000 people in Dublin and Sligo to take part and will measure their exposure to the virus using antibody blood tests.
It comes as one more person with Covid 19 has died here and there are 8 new confirmed cases.
HSE National Clinical Director for Health Protection, Dr. Lorraine Doherty, says the blood tests will find out what antibodies they have.
"These tests are not diagnostic tests, they're designed to check for the presence of antibodies which may be present in people exposed to Covid.
"Basically what we will get is an idea of people who have had a a sub clinical infection, people who may have been asymptomatic, and people who may have had a mild illness that they didn't think was Covid, but in fact when we test them they're demonstrating antibodies to Covid."
