Q&A: Air passengers could face swab tests to curtail the spread of Covid-19

He said the testing of incoming passengers had been successfully carried out in other countries.

The logistics are still vague - just how would this work and how effective would it be?

Nasal swab test

If they opt for a nasal swab test, it will involve a long stick with a very soft brush on the end being placed up the passenger's nose. This will collect a sample of secretions.

This can be uncomfortable because cells and fluids must be collected.

The swab must be taken to a laboratory for analysis. It is unclear if it is planned to set up a lab at the airports or send the specimens to a nearby facility. This underlines the complexity of what is involved if it goes ahead. The passenger would have to wait for several hours for a result.

Missing people who are positive

The testing is not foolproof and, because of the incubation period of the virus, somebody who is positive may be cleared as negative. Ideally people need to be tested twice, with a second test performed about seven days later.

Somebody who is positive but told they are negative runs the risk of unwittingly passing the infection on.

If somebody tests positive, the State will also have to work out if they will offer them specialised accommodation to allow them to safely self-isolate.

Rapid test

Tests which can have a turnaround time of less than an hour are being looked at by some airport authorities. They are less complex than the PCR test and would avoid the need to send a swab to a laboratory. The reliability of the test would need to be confirmed before it was applied here.

Going Awol

People who are returning home or arriving as tourists should self-quarantine for two weeks, but it is not mandatory. It is not being followed by everyone. The Department of Justice said yesterday that until late June, 100pc of passengers arriving here were called by its Border Management Unit (BMU) on behalf of public health officials.

Since the beginning of July, given the increase in passenger numbers, the BMU - on behalf of public health - is making follow-up calls to a proportion of passengers.

The mandatory locator forms they fill out on arrival with their details and destination are selected randomly. Currently, a proportional group - between 10pc-20pc - from every flight is contacted by phone.

Since the introduction on May 28 of the mandatory requirement to complete the form, just three people at Dublin Airport have refused to do so and they have been referred to the Garda National Immigration Bureau.

It said the key to successful enforcement of the forms was to front-load as much of the process as possible, to ensure the forms are completed before passengers arrive in Ireland.

This involves the airlines and ferry companies doing as much as they can to ensure compliance before boarding, reminding passengers about the mandatory nature of the forms during the journey, and the ports and airports providing a further opportunity to complete the forms in as socially distant an environment as possible on arrival. The production of an online version of the Passenger Locator Form is currently being prioritised by the Government.

Figures show that from July 1 to July 13, 52,743 people arrived at Dublin airport.

A sample of 5,042 people was taken; 1,510 of these are excluded for reasons such as being exempt because they were travelling to Northern Ireland.

Officials in the Department made 3,532 calls to passengers who were supposed to be self-quarantining.

Just 1,698 of these were answered - only 48pc.