Mass-goers are being advised not to receive Communion hosts on the tongue to help reduce the spread of flu.
They are also being encouraged to nod or bow instead of shaking hands in the "exchange of peace".
The HSE also says members of the clergy or congregation should not attend Mass if they are ill.
The body warned this week that, though spring is in the air, flu will continue in the community for up to 10 more weeks, before it's completely gone.
The HSE also said 55 people had died from the flu so far this winter. The majority of these were over 65 years of age with fewer than 10 being children.