Researchers at Trinity College Dublin are searching for people who may have innate resistance to Covid-19 to take part in an international study.
Those who have shared a bed with someone with Covid-19 without contracting the disease themselves are of particular interest to the researchers.
The study, which aims to understand why some people are "naturally resistant" to Covid-19 infection, could have implications for vaccine development and public health measures.
Professor Cliona O'Farrelly, the principal investigator of the study said 14 countries are involved and they are ideally looking for people who resisted Covid-19 before vaccination as well as after the discovery of the Omicron variant.