Over 5,000 people are being invited by the HSE to take part in a new study, which aims to provide an overall estimate of how many people in Ireland have been infected with COVID-19.

The Study to Investigate COVID-19 Infection in People Living in Ireland (SCOPI) will measure exposure to the virus in the population using an antibody blood test.

More than 5,000 people living in Dublin and Sligo are to be sent letters inviting them to participate.

According to the HSE, Dublin and Sligo were selected as sample locations because they represent areas of the country with higher and lower known levels of infection respectively. Therefore using a representative sample from each of these counties will provide an overall national estimate of infection within the Irish population.

The intention is then to repeat this research in other parts of the country over the coming year.

Those who consent to take part in the study will be asked to complete a short questionnaire by phone. This will be carried out by trained staff on behalf of the HSE's Health Protection Surveillance Centre (HPSC).

In addition to the questionnaire, participants will also be asked to provide a blood sample to test for antibodies. The sample will be taken by a phlebotomist in a local centre arranged by the HSE.

Participants will be provided with their individual results and those who are found to have antibodies for COVID-19 will be asked to take part in a follow-up study.

This will include further questions relating to COVID-19 symptoms and involve three further blood tests over a 12-month period.

Antibodies to COVID-19 are produced over several weeks after infection with the virus. The presence of antibodies indicates that a person was infected with COVID-19, irrespective of whether they had severe or mild disease, or they were asymptomatic.

It is hoped that the findings will provide more information about how long antibodies last and what protection they may provide against new COVID-19 infection.

"Seroprevalence (blood test) studies are really important to help us understand the true level of infection in the population. When the results are available, we will have valuable information on the level of infection by age group and also the extent of asymptomatic infection, informing our national public health responses to COVID-19," commented Dr Lorraine Doherty, the HSE's national clinical director for health protection.

According to Dr Cillian de Gascun, director of the National Virus Reference Laboratory, the antibody test being used in this study has already proven to provide accurate results.

"It has recently been shown in international studies to be both sensitive, in that it detects the majority of people with antibodies, and specific in that a positive test is an accurate reflection of infection," he noted.

The HSE said that in order to ensure that both males and females of all ages, who broadly represent the wider population, are included, the statistical technique of selecting a random sample of the population has been chosen.

As a result, the study is not open to volunteers from the general public.

The HSE is encouraging anyone who receives a letter to participate.

"This is an important study and those who participate are contributing to essential research that is of benefit to society, and helping with the national pandemic response," the HSE said.

Initial results are expected in late August.