COVID-19 case definition updated to include notification of positive results from Antigen Detection Tests, which have now been validated for use in the public health system


The COVID-19 interim case definition for Ireland has been updated as of Wednesday 27th January 2020. It has been updated to include notification of positive results from Antigen Detection Tests (ADTs) carried out in the public health system.

ADTs are immunoassays that detect the presence of specific antigens on the surface of the virus, and identify people who are infectious, when virus levels in the body are likely to be high. Though less sensitive than PCR tests, they can be performed outside the laboratory (known in this instance as Rapid Antigen Detection Tests (RADTs)), and generally take less than 30 minutes to perform, providing rapid information for detection, management, and control of the spread of infection.

Following independent and setting-specific validations of ADTs undertaken by the HSE Antigen Project Evaluation Working Group, an operational framework  identifying the settings for use, the criteria for ADTs and the standards for use in acute hospitals and community settings has been prepared. Guidance on the use of ADTs has also been developed. In general, tests will be carried out in those within 5 days of onset of symptoms, or within 7 days of last exposure if they are close contacts of a case.

In the acute hospital setting, the first setting where ADTs will be used, they may be used for:

  • Triage of patients in emergency departments and in ambulances arriving at department pending admission to the emergency department;
  • To support early diagnosis in hospital outbreaks, including testing of symptomatic Health care workers;
  • In situations where ADTs can reduce pressures on the hospital’s capability for rapid PCR testing.

In the community setting, as soon as practical arrangements have been finalised, ADTs may be used as part of the response to outbreaks in symptomatic vulnerable populations and their close contacts following Public Health Risk Assessment, when there is evidence of widespread community transmission. The vulnerable populations include staff and/or residents of long-term care facilities, homeless hostels, residents of direct provision centres, prisons, Irish Travellers etc.