Dr Tony Holohan has warned against the use of rapid antigen testing as a ‘green light’ for activities during the pandemic.
He said there’s not enough evidence yet to support the widespread use of antigen testing to facilitate international travel.
He said NPHET would be fully open to the use of the rapid tests in any setting, as long as there is 'validated' research and studies on the benefits of their use.
However, he argued that they can't simply "start rolling out tests on the basis of people think it's a good idea, without good quality scientific evidence."
The Oireachtas Transport Committee last week heard arguments from a Harvard Medical Professor that antigen testing is more effective than PCR testing for international travel.
Dr Michael Mina explained that antigen testing can quickly show if are infectious, which he believes is more advantageous for travel than a PCR test taken a few days before travelling.
Members of the Committee have urged the CMO to explain NPHET's resistance to antigen testing for international travel.
Following that request, Dr Holohan is appearing before the committee today, alongside other NPHET members including Dr Ronan Glynn, Professor Philip Nolan and Dr Cillian De Gascun.
In his opening remarks, Dr Tony Holohan said there is still much we need to learn about these tests and their actual - as opposed to hypothetical - benefits and limitations.
He said: “As the evidence evolves - and assuming that that evidence is supportive in relation to rapid antigen testing - we are more than willing to support its further use where appropriate real-world evaluation indicates that it can bring added benefit in the pandemic response.
“Ultimately, however, based on knowledge to date, the safest way to reopen society, including to international travel, will be to continue to control disease incidence through a range of public health measures which are continuously reviewed... along with progressing the national vaccination programme to ensure as many people as possible within the population are protected through immunisation.”
In follow-up answers, he said they can't just start rolling out testing because some people think it's a good idea - saying good-quality studies and research are needed first to validate the effectiveness of the tests.
However, he agreed with the suggestion from the committee's chair Kieran O'Donnell that pilot schemes are needed to examine the efficacy of antigen testing before flights.
Earlier, an Oxford professor described NPHET's stance on antigen testing as 'old-fashioned' - suggesting there are problems with the current approach of relying on a PCR test two days before a flight.