More than 100 Covid outbreaks are occurring each week, most of which are happening at social gatherings and in workplaces, the National Lead for Testing and Tracing at the HSE has said.
Speaking on RTÉ's Today with Philip Boucher Hayes, Niamh O'Beirne said there are an increasing number of outbreaks in these settings with people returning to the office.
Transport to and from work is also a challenge, she said.
There is anecdotal evidence of people going to work with symptoms and "that's a challenge both for those vaccinated and unvaccinated", Ms O'Beirne said, and reminded those not to attend work if they are symptomatic.
She said while the office space itself may be quite safe, transmission tends to occur during breaks, such as coffee and lunch breaks, as well as travelling to and from work. Car-sharing can tend to be more crowded, she added.
The importance of ventilation in a work space cannot be over-stated, as well as mask wearing as people move around the office, she said.
There have been quite large outbreaks in certain environments including weddings, Ms O'Beirne said.
She said that "generally speaking, that type of environment, if Covid does get into it, can be quite difficult".
With the number of cases reported by the Department of Health passing 2,000 on Saturday, the focus is on "forward tracing", which she said is making sure anyone who was in contact with a detected case is aware of that.
She urged people to identify both vaccinated and unvaccinated close contacts so they can advise who needs to get tested.
The HSE is also dealing with about 30 flights a day on which a positive case has been identified, she said.
7.5% of those who tested positive for Covid would have travelled abroad in the recent past, she said.
Transmission on flights is quite low, and those who test positive after flights tend to be with a person who is Covid positive, such as family members or friends travelling together, she said.
She added that it is "probably more likely if they're with them, that they got it before the plane".