At least seven out of every 10 citizens would need to get the swine-flu vaccination for it to have a significant effect on reducing rates of transmission in the country.

Health authorities are concerned members of the public may be slow to avail of the vaccine due to fears about the 'fast-tracking' of safety tests on the vaccine.

They are also aware that traditionally low uptake rates of such vaccines, most particularly among health professionals, could put the potential effectiveness of any mass vaccination programme at risk.

In the past week alone, the virus forced three Irish colleges in the Donegal gaeltacht to close after outbreaks occurred among their students. Further school closures are expected when the new term gets underway next month.

The HSE is preparing to launch a public information campaign in the coming weeks to encourage people to get the vaccine and to assuage any safety concerns individuals might have.

Speaking at a press briefing last Thursday, the HSE's head of health protection Dr Kevin Kelleher stressed it was important everyone availed of the vaccine when offered it.

He said swine-flu batches are expected to arrive here in the autumn, subject to licensing and safety checks, although no definite date has yet been set.

Asked what rate of uptake of the planned swine-flu vaccine would be necessary for the vaccination programme to be deemed effective, a spokeswoman for the HSE said a rate of "70% or higher would significantly reduce the transmission in the community".

However, previous uptake rates of the regular flu vaccine among medical-card holders are only around 60% – and uptake rates amongst healthcare workers are just 20-30%.

This suggests public health authorities could face significant challenges in achieving their targeted rates of uptake.

The spokeswoman said the HSE will be seeking the "maximum possible uptake for the pandemic flu vaccine.

"We will not be vaccinating anyone until we are satisfied that it is absolutely safe to do so," she said. "We will be seeking a significantly higher uptake rate amongst healthcare workers... It will be critical that as many healthcare workers as possible get the vaccine to ensure that they are not transmitters of the virus to vulnerable patients and to ensure that they can care for the sick as infection rates amongst the public rise."

Pharmaceutical company Baxter Healthcare has recently completed its first commercial batches of the H1N1 swine-flu vaccine, and has discussed potential distribution plans with five national health authorities, including Ireland's.

The company has commenced its licence application for the vaccine in the EU, with regulators in the EU and the US expected to 'fast-track' approval of swine- flu vaccines to ensure they available for the start of the northern hemisphere winter.

The World Health Organisation has repeatedly stressed that such 'fast-track' procedures do not reduce safety, while acknowledging concerns had been expressed about this issue.

Latest figures from the state-run Health Protection Surveillance Centre reveal a total of 18 outbreaks of swine flu have been reported to date here, including one in a hotel.

The HPSC report says 13 outbreaks occurred in family settings, one was in a hotel, one involved travelling companions and three occurred in educational settings.