The recommendation announced by the Government that face masks should now be worn in crowded work places, places of worship, and also in busy crowded outdoor spaces is a new departure.

It follows a recent evidence summary undertaken by HIQA about the effectiveness of face masks for reducing the risk of spreading Covid-19, as well as observations about successful practices in other countries.

The National Public Health Emergency Team had given the matter significant consideration during their eight-hour meeting on Wednesday this week and the measure was specifically recommended by Chief Medical Officer Dr Tony Holohan on foot of that meeting.

His recommendation was that face masks, but not visors, should be used in all communal areas in indoor workplaces, including shared offices, corridors, and other shared workspaces.

He also recommended face masks, but not visors, should now be worn in all places of worship, as well as in busy crowded outdoor spaces where there is significant congregation and where social distancing may not be possible.

It is all a far cry from the repeated arguments against the public wearing face masks adopted by NPHET and Dr Holohan during the earlier months of the pandemic.

Back then, Dr Holohan and others trotted out a litany of reasons why face masks would be an ineffective measure for the general public.

We were told, for instance, that people could become contaminated by handling face masks inappropriately, that people wouldn't wear the properly, that they weren't as air tight as medical grade face masks and so would not contain the virus, that many people for a variety of reasons, including medical reasons, may not be able to tolerate them and shouldn't be asked to wear them.

We were also told that the experts did not want the public competing with the HSE to purchase what was in those early days of the pandemic a critical, but scarce enough, piece of personal protective equipment.

The fact that the attitudes of our public health experts have changed since then underscores how much we have learned through scientific experimentation and analysis over the past been nine months.

The HIQA report that clinched the argument was published earlier this month.

It concluded unequivocally that the use of face masks should be part of a comprehensive package of prevention and control measures to limit the spread of certain respiratory viral diseases, including Covid-19.

Face masks, it pointed, will provide protection for the wearer themselves when in contact with an infected individual.

But they will also prevent onward transmission to other people from a person who is already infected.

The HIQA report spoke of model simulations using data relevant to Covid-19 dynamics in the US states of New York and Washington, which suggested that broad adoption of even relatively ineffective face masks may meaningfully reduce community transmission of Covid-19 and decrease peak hospitalisations and deaths.

It also said that when face masks are used by the public all of the time, and not just from the first onset of symptoms, then the effective reproduction number for the virus can be decreased below 1, leading to the mitigation of epidemic spread.

It concluded that any type of general mask use is likely to decrease viral exposure and infection risk on a population level in spite of imperfect fit or imperfect adherence - the exact opposite of the earlier arguments put about by the experts.

But the HIQA study also underscored that face masks and coverings should not be viewed in isolation.

They need to be seen as part of broader policy packages because they are insufficient on their own to provide an adequate level of protection or source control.

And that is precisely what is now happening in Ireland.

In its efforts to ensure that people can enjoy the festive season, the Government had to balance a host of different risks.

The National Public Health Emergency Team has warned that the daily case load of confirmed Covid-19 infections is far higher than they would like.

This means that the force of infection in Ireland, although lower than almost anywhere else in Europe, is still stronger than the authorities here would like. As a result we are vulnerable to the impact of any increase in the rate of spread of the virus.

Add to that the certainty of increased social interactions over the coming month.

According to modelling of the pandemic done on behalf of NPHET, we are very likely to find ourselves dealing with a third wave of infections by early January.

NPHET has also warned the Government that the model is predicting that this upcoming third wave will ensue much more rapidly and with greater mortality than the wave of infection we are coming out of right now.

In light of all these risks, it follows that whatever can be done to compensate for the chances we are taking, by moving from Level 5 to Level 3 of social restrictions, must be done.

That is where having to wear face masks in all communal settings, in indoor workplaces, as well as in crowded outdoor spaces, comes in.

There is now broad agreement among scientists that this is a really important measure that will help to reduce the spread and compensate for some of the risks that we are about to take.