Q&A: How the new antigen test system will work for close contacts

Rapid tests can be completed at home with results in 15 minutes

An antigen test is quicker but less reliable than a PCR test. Photograph: iStock
An antigen test is quicker but less reliable than a PCR test. Photograph: iStock

Close contacts of confirmed cases of Covid-19 will be sent free antigen tests by post to test themselves for the virus as long as they are fully vaccinated and do not have any symptoms. Here is a guide to how it will work:

What is an antigen test?
Covid-19 antigen tests are rapid tests used to detect coronavirus. The test can be completed at home, using a swab to take a sample from your nose.

How does an antigen test differ from a PCR test?
PCR testing is the most reliable way of diagnosing Covid-19 and is the main type of test used by the HSE. The PCR test looks at the genetic material of the virus with swabs taken at testing centres that must be sent to a lab for analysis, meaning it can take days for a result to be returned. An antigen test is quicker but less reliable than a PCR test. The test sample does not have to go to a lab and you generally get your result in 15 minutes.

What is the HSE doing with antigen kits?
From Thursday the HSE will begin registering fully vaccinated, asymptomatic close contacts for antigen tests to be done at home.

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What if I am a close contact and not fully vaccinated and/or symptomatic?
Close contacts who are not fully vaccinated and/or symptomatic will be referred for a PCR test.

Will the antigen tests be delivered to my home?
A contact tracer will be in touch to ask for an address to post your antigen tests. You will be posted out a box of five antigen tests and will be asked to do three: the first test on the day you receive the kit, the second test two days later and the third test two days after that.

What if the antigen test comes back positive?
If an antigen test comes back positive you must self-isolate at home and book a PCR test. Those whose antigen tests are negative are asked to report their negative results via the HSE website. The HSE recommends doing all three antigen tests, even if one of the tests is negative.

What if the result of my antigen test comes back as invalid?
The HSE has said an invalid test means the test did not return a positive or negative result. If any of your antigen tests are invalid, you are advised to use a spare test.

Will I have to pay for the antigen tests?
The antigen tests provided by the HSE are free.

Are antigen tests suitable for children?
Yes. The HSE has advised that children aged 13-16 should be supervised by a parent or guardian when they are doing an antigen test.

Why are antigen tests being used now by the HSE?
The change was made on foot of a recommendation from the National Public Health Emergency Team (Nphet), which up until earlier this month had resisted the wider use of antigen testing. They have been long resisted by public health officials because of concerns about their accuracy. The Minister for Health Stephen Donnelly acknowledged on Thursday that progress on antigen testing had been slower than he would have liked.

Where else are antigen tests being used?
Antigen testing is also being done in hospitals, further and higher education settings, creche and childcare services and places where there is an outbreak of Covid-19. The rapid testing expert advisory group, chaired by Prof Mary Horgan, has also been asked to see if rapid testing could be used as a component of the Covid-19 pass for those who are unable to get fully vaccinated on medical grounds.

Sarah Burns

Sarah Burns

Sarah Burns is a reporter for The Irish Times