Putting in place strict coronavirus restrictions for just three weeks would have led to a risk of a 'rapid' surge in cases shortly before Christmas, the Chief Medical Officer warned the Government.
The letter Dr Tony Holohan wrote to Health Minister Stephen Donnelly following NPHET's meeting last Thursday has been published.
In it he explained that level three measures were not working and urged Government to move to level five as soon as possible.
It was the second time NPHET had recommended a move to level five - with the Government originally opting for level three instead.
However, the country will now move to a second lockdown from tomorrow night.
After NPHET's meeting last Thursday, Dr Holohan told Minister Donnelly that there could be between 1,800 and 2,500 coronavirus cases per day by Halloween if trends were to continue.
He also warned that up to 600 COVID-19 patients - including over 100 in critical care - could be in hospitals by the end of the month.
The letter states that if strict measures were in place for three weeks, there would likely be a surge in the spread of the virus.
The CMO explained that if the R number was reduced to 0.5 for three weeks, case numbers would drop to around 250-300 a day - but once restrictions were lifted, and the R number returned to 1.4, a 'rapid re-escalation' would occur in the middle of December.
However, he suggested case numbers could be down to 50-100 per day at the end of six weeks, and wouldn't rise to 300 until early January.
Level five recommendation
The CMO said there had been a 'significant deterioration' in the situation since NPHET's first level five recommendation.
Extract from Dr Tony Holohan's letter to Health Minister Stephen DonnellyHe said: "The NPHET continues to believe a more aggressive strategy is necessary to achieve the levels of suppression that are necessary to bring this disease back under control in a shorter time period, thus mitigating increases in hospitalisation and mortality and allowing us to get to a point where restrictions can be lifted more quickly."
He also noted that public health officials' ability to carry out 'robust and timely' contract tracing had become constrained due to the sharp increase in new cases.
Dr Holohan said NPHET felt all the 'triggers' for a move to the highest level of restrictions had been met, although added that they believed schools should remain open.
He added: "NPHET firmly believes that an escalation to level five is inevitable and that the earlier this proactive action is taken, the greater chance there is of quickly reversing the current trajectory of the disease and thereby limiting the impact on public health, both physical and mental, and protecting vulnerable groups, and non-COVID health services and education services."
Cabinet signed off on the proposal for a move to level five yesterday, with some changes to the initial guidelines to allow for more people to attend weddings and funerals.
