Holohan’s views on antigen tests ‘inaccurate’, Harvard professor says
Chief medical officer (CMO) Dr Tony Holohan’s views on rapid Covid tests are “inaccurate”, an expert on infectious diseases told politicians on Wednesday.
Michael Mina, assistant epidemiology professor at Harvard University, challenged the CMO’s opposition to antigen screening at an Oireachtas committee which heard that the Republic was the EU’s “most disconnected” state following months of travel bans.
Dr Holohan has warned that cheaper, quicker antigen tests for the virus are only 50 per cent accurate, prompting the Government to bar their use for international travel.
Prof Mina dubbed the CMO’s assessment as “just inaccurate”, saying it failed to take into account that rapid tests were used to limit Covid’s spread, rather than to diagnose patients.
He explained that antigen tests identified people at their most infectious, the “population you want to exclude” from flights, big sporting occasions and other events.
The US academic told the Oireachtas Committee on Transport and Communications Networks that getting results quickly was more critical to halting Covid’s spread than detecting it down to its last traces.
“Antigen tests are sufficient to detect anyone who is likely to spread the virus,” Prof Mina said.
He pointed out that the slower, more expensive PCR tests, favoured by the CMO, detect Covid for up to 30 days, while anyone carrying the virus was at their most infectious for just 10 days.
On that basis, a test designed to limit Covid’s spread only needs to have sensitivity rates of 30 per cent to 40 per cent, he said. “So 50 per cent is actually a good value if that test is only meant to detect infection,” Prof Mina noted.
He told the committee that data increasingly showed that using rapid screening before large gatherings could prevent 90 per cent to 95 per cent of transmissions.
Prof Mina maintained that antigen testing passengers an hour before a flight was more likely to prevent virus transmission than requiring a negative PCR result from several days before, which the Republic’s authorities demand.
“If somebody uses a PCR test two to three days before a flight and they get a negative result, by the time they walk on that flight they could literally be at the peak of their infection. Antigen tests would detect those people,” he said.
“If you are trying to diagnose somebody, then use a PCR test, but if you’re trying to stop the spread of infection, then use a rapid test,” Prof Mina stressed.
Governments should continue using antigen tests even where large numbers of people have been vaccinated, as they could still carry enough quantities of the virus to infect others, he cautioned.
‘Most disconnected in Europe’
Earlier, Dr Niamh Power director of V1 Medical, which provides Covid tests to airlines and shipping companies, pointed out that the Republic was an “outlier” in not allowing rapid antigen screening for travel.
Chairman, Kieran O’Donnell TD, said that the committee had invited Dr Holohan and other members of the National Public Health Emergency Team to appear to explain their stance on rapid testing.
Committee member, Michael Lowry TD, argued that the CMO and his staff should be quizzed on their opposition to quicker, cheaper, antigen tests for travel.
“They must be given the opportunity in public to explain their rationale and their decision to ignore scientific evidence,” he said.
Dr Power said that V1 Medical and other companies providing Covid tests for travel had yet to hear from Government what role they will play in implementing the EU digital Covid certificate.
She said that she had spoken to several organisations, including one of the Republic’s biggest travel medicine practices and one of the larger companies providing tests at Dublin Airport, and the Government had not contacted them.
The Government has pledged to introduce the certificate, meant to restore freedom of movement in the bloc, on July 19th, as part of its plan to reopen travel.