NPHET is recommending people who frequently go to nightclubs, bars or restaurants take an antigen test twice a week.
Chief Medical Officer Dr Tony Holohan has also asked the Government to consider extending the use of COVID-19 Certs beyond the hospitality industry.
The Cabinet Sub-Committee on Covid-19 will consider their recommendations on Monday.
In his latest letter to Health Minister Stephen Donnelly, Dr Holohan says there is "significant and sustained impact" across all aspects of the health service due to the current level of COVID-19.
This includes public health, testing and tracing services and general practice - as well as broader primary care services and the acute hospital system.
On testing, he says people who regularly engage in "higher risk activities" should consider self-testing on a regular basis.
He says this would be a minimum of twice weekly, spaced out by three days, for activities that are ongoing over a period of time.
These activities could include going to bars, restaurants, nightclubs, the cinema, multi-household visits, playing indoor contact sports, and car sharing with people from other households.
People should also consider using a single self-test before doing higher-risk activities, he adds.
Facemasks and distancing
NPHET says other basic measures, such as physical distancing, should be re-emphasised with the development and roll-out of a 'Layer Up' communications campaign by the Government.
This asks people to continue to adopt the full range of protective behaviours.
On face masks, "a further strengthening of communications targeted at individuals and sectors" is recommended.
This will focus on how to wear a mask correctly, and where mask wearing is mandatory or advised - including crowded outdoor settings.
There is also to be targeted communications to people who should be wearing medical grade face masks: those over-70 and medically vulnerable, and those with symptoms.
On the COVID Certs, Dr Holohan recommends a campaign targeted at people and sectors to continue to focus on clarity on where it is required - and the importance of implementation.
There will also be "a sustained focus" on inspection and enforcement processes, he adds.
NPHET also say they will give consideration over the coming period "to implications for the COVID pass system arising from the COVID-19 booster programme".
The letter adds that Government should give consideration "to the extension of its application to settings where there is high risk of transmission, through close contact or other activities, not yet covered by the current regime."
And the group says people should be reminded of the importance of ventilation - in both private households and public settings - as we move into winter.
While NPHET say advice to work from home - where possible - should be re-instated.
It says the return to workplaces involves a potential increase in contacts, both directly - in the workplace itself - and indirectly - when travelling to or from work.