Ireland's Chief Medical Officer has urged the public to be aware of the "most important" change to the country's public health advice.
Rules on close contacts and self-isolation were eased on Friday "in light of available evidence, expert views and the international experience of Covid-19".
The Department of Health said: “While we are reducing the requirement to self-isolate and restrict movements for cases and close contacts respectively, we are strengthening guidance relating to mask wearing and reduced social contact for the full ten days following diagnosis or last known close contact.
Under the new rules, people who close contacts but do not have symptoms, are aged 13 and older and boosted are not required to restrict their movements.
However, they must use a well-fitted medical grade or FFP2 face mask for 10 days and take regular antigen tests over seven days.
Dr Tony Holohan reiterated the importance of the new mask-wearing rules after the latest change to the public health advice.
He was commenting after 11,139 further Covid cases were reported on Monday, including 6,329 positive PCRs and 4,810 positive antigen test registrations.
The CMO said: “As we continue to adjust to the latest changes to the public health advice relating to isolation and restriction of movements for cases and close contacts, it is important to remember that the most important change relates to mask wearing.
"It is now recommended that medical grade or FFP2 masks are used by:
- anyone 13 years and older who is a confirmed case, a close contact or who has symptoms suggestive of Covid-19
- over 60s and vulnerable people of all ages in indoor or crowded outdoor places
- anyone visiting a healthcare setting or when visiting those who are vulnerable to Covid-19 in any setting
"Masks can play a key role in reducing transmission of Covid-19 if made correctly, well fitted and worn properly – that is they cover the nose, mouth and chin."
Dr Holohan also urged people to avail of their booster jabs as he gave an update on vaccination figures over the past week.
“The best way to protect yourself against the most severe impacts of Covid-19 is to get your booster dose of Covid-19 vaccine. The evidence shows that people who have received a booster are less susceptible to infection and, if infected, are less infectious to others," he said.
“According to our Amarach research, 68% of those aged under 35 years, who have received a full, primary course of Covid-19 vaccination but are not yet boosted, said that they would receive a booster dose if they were offered it next week.
"It is important to remember that you don’t need to wait for the HSE to contact you about your booster appointment. You can book an appointment online on www.hse.ie, drop into your local pharmacy or contact your GP.
“In the last week over 46,000 children aged 5-11 have been vaccinated in Ireland. Vaccines are a very safe and effective way to protect children from the risk posed by Covid-19 infection.
"The HSE are operating special child-friendly vaccine clinics. Please ensure to visit www.hse.ie for trusted information on Covid-19 vaccines or to book an appointment."
He added: “Continue to layer up on the basic public health measures, including vaccination, to protect yourself and your loved ones from infection.
"Wear the appropriate mask recommended for you, practise social distancing and good hand hygiene, work from home unless necessary to attend in person, avoid crowds and ensure indoor spaces and public transport are ventilated by opening windows regularly.”