Thousands of employees who are offered the flu jab for free in the workplace are facing delays to vaccinations this winter because of later deliveries of the injection.
Several pharmacists are also reporting they are running low on stocks and cannot keep pace with demand from customers for the vaccine.
The delay is being blamed on later than normal shipments of the vaccine by some drug companies due to the World Health Organization last spring taking longer to select the virus strains to be covered by the jab.
It allowed companies to improve the match of strains of H3N2 viruses which are due to circulate here this winter.
The knock-on effect is that some employers in this country have had to reschedule the dates planned for offering the vaccine to workers.
However, the HSE said its supplies distributed to GPs and hospitals are on track.
"The HSE constantly monitors the supply and distribution of flu vaccine in Ireland," said a spokeswoman.
"There has been no shortage and no anticipated shortage of flu vaccine supplies for this season's influenza campaign.
"A fortnightly delivery service is in place for this busy season and all locations at this stage have had an opportunity to have received their full requirement, if they choose."
The total contracted volume of influenza vaccine for the 2019 and 2020 season, in excess of last winter's, has been received by the HSE.
"Ireland is one of the earliest of European counties to have secured their full requirement of vaccine," the spokeswoman said.
The HSE said it could only comment on its own stock.
"Any shortage in the private market is not within the control of the HSE."
Flu is circulating here but it is still at low levels.
However, a number of people have had to be hospitalized as a result of complications of the flu.
No deaths due to the flu have been reported to date this winter.
All strains of flu covered in the vaccine have been detected this winter.