Aengus Ó Snodaigh (Dublin South Central, Sinn Fein)
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687. To ask the Minister for Health the reason the polymerase chain reaction, PCR, test is being used to test for Covid-19 rather than an antigen test; if there are significant cost or accuracy differences; and if he will make a statement on the matter. [3692/21]

Stephen Donnelly (Wicklow, Fianna Fail)
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The Health Service Executive has adopted RNA PCR as the gold standard test for diagnosing Covid-19 cases, as part of the HSE test and trace strategy, consistent with international best practice, and approved by the National Public Health Emergency Team (NPHET). This platform is deployed in acute hospitals, the NVRL and HSE’s commercial partners.

It should be noted that testing for Sars-Cov2 does not confirm that an individual with a 'not detected' result is not incubating the infection or the level of virus is below detectable levels at the time of the test. The HSE has worked intensively over the last number of months to put in place a comprehensive testing and tracing operation and despite the very significant increase in demand over the last number of weeks, the median time for community referral to appointment is now 0.2 days with 95.7% of GP referrals provided with a COVID-19 test appointment within 24 hours.

While rapid antigen diagnostic tests (RADTs) are described as rapid, and simple to perform, they are not designed to be delivered in large numbers. RADTs are most effective in detection of symptomatic cases, particularly where there is swabbing capacity on-site, when symptom onset is within the last 5 days and when the likelihood of test positivity is greater than 10% among the target population.

Validation studies, both here in Ireland and in Europe are showing significant disparities in sensitivity and specificity of tests versus manufacturer claims. The studies also show that performance in symptomatic patients is much better than in asymptomatic patients. In asymptomatic patients, sensitivity results are being shown to be below the minimum performance requirements set by the World Health Organization and the European Centre for Disease Prevention and Control.

The National Public Health Emergency Team has endorsed recommendations on the use of Rapid Antigen Detection Tests (RADTs) as a supplement to PCR testing in certain situations, and particularly when the availability of PCR tests may be limited. The HSE is currently considering the use of RADTs for diagnosis of symptomatic persons and their close contacts in PCR confirmed outbreaks, and / or symptomatic persons where there is a high suspicion of an outbreak, pending PCR confirmation, if faster presumptive results will inform public health action.

On an ongoing basis, NPHET considers and reviews, based on public health risk assessments, how best to target testing to hunt the virus in populations where it’s most likely and where it will do most harm. This includes keeping Ireland’s testing policy under continuing review.