INTRODUCTION: The HSE National Drug Treatment Centre is an inner city drug treatment centre in Dublin which provides opiate agonist treatment (OAT) to approximately 565 patients, many of whom have complex care needs.

OBJECTIVE: This study was conducted to determine seropositivity to the COVID-19 virus in patients attending NDTC, and to establish if patients tested had any clinical symptoms of this disease since March 2020.

METHOD: All patients attending for OAT were invited to participate and 103/565 patients agreed. The patients were tested for the presence of serum antibodies to COVID-19 in a single sample collected over a 4-month period (July-October 2020). A questionnaire was administered at the same time as sample taking.

RESULTS: Results showed that the majority of patient samples (100; 97%) tested were negative for the presence of antibodies to COVID-19. There were only two confirmed positive results (1.9%) and one equivocal result (1%). None of the approximately 565 attendees at the HSE NDTC presented with serious illness indicative of COVID-19 throughout the three waves of the pandemic, nor were any deaths due to COVID-19 reported.

CONCLUSION: These findings indicate (a) possible low level of exposure to COVID-19 among this patient cohort or (b) that those patients who have been exposed have not developed or maintained detectable antibody levels, nor developed symptoms of the disease. Public health measures could explain the low level of COVID-19 in this cohort. The findings are also consistent with the possibility of a protective effect of OAT medications on development of the disease.