Professor Mary Keogan:

Validation is a normal part of diagnostics. Every test put into practice needs to be validated. This is not confined to antigen testing and the need over the past year. There have been four PCR tests which have not met the criteria to be introduced into our hospitals. Had we failed to validate, we would have missed the diagnosis in a number of patients, allowing outbreaks to proceed and denying patients appropriate treatment. Validation is a key part of the diagnostics for any test.

Internationally and in all of the countries the Deputy mentions, manufacturers' claims of sensitivity and specificity have not been borne out in many cases by independent field evaluations. In line with the European Centre for Disease Prevention and Control, ECDC, position, we need to do independent field evaluations to confirm or refute the manufacturers' claims. Most of these antigen tests were developed to investigate symptomatic individuals. The findings in symptomatic individuals cannot be extrapolated to asymptomatic individuals. It is a key part of our public health response that symptomatic individuals should not be going to school, work or events and that they should not be travelling. No test is perfect, and so, if symptomatic people continue to go about their business as if they are asymptomatic, that will cause problems. We are talking about the results in asymptomatic people.

One myth with antigen tests is that they are rapid and easy. To do one test is rapid and easy but to do 100 tests is extremely labour intensive. For example, in the Barcelona conference at the end of March, 80 nurses were deployed to work 12-hour days to get 5,000 people tested. It is key that members of this committee understand the enormous work involved. Self-testing is promoted as a way to get around this but these tests are open to manipulation. You can produce a false negative or positive test by using carbonated beverages. Therefore, self-testing is not used in any jurisdiction for a test-to-enable approach.