Dr. Cillian De Gascun:

The Deputy has identified one of the challenges. We are very fortunate that HIQA has done a huge amount of work in this area and examined what is happening in other countries and in the literature. Unfortunately, the evidence base is not in the literature regarding the performance of antigen tests in the real-world setting. We have a very good test in the polymerase chain reaction, PCR, test at this point and we would need a good reason to move away from it. What we often see as new tests are developed and new pathogens emerge is that the first generation of tests is imperfect but the second and third generation tests evolve, become more refined and get better.

It is completely possible that the second generation of antigen testing will become more easy to use, sensitive and more specific. The specificity of antigen testing is not too bad at this point in time which should be acknowledged. It is really a question of the sensitivity and the concern that we will miss cases. That is why testing in whatever setting has to be taken in conjunction with restriction of movements in a travel setting and with a period of quarantine, purely because no test is perfect. A test only gives an indication of a point in time. For example, I could have had a test outside here this morning where the virus was not detected. I could well be infectious now regardless of what the test said purely because of the way that the virus replicates over time, the virus load increases, and therefore becomes more easy to detect. It is a point in time test and we need to be careful about not inferring too much on the basis of a single result.