Two more people were awaiting swine flu test results in Northern Ireland tonight after 11 other suspected cases proved negative.
All 13 had recently returned to the region from the affected countries of Mexico and the USA.
They were among 29 people who have contacted local doctors worried about their symptoms since the health scare broke.
So far as many as 159 people have died from swine flu in Mexico, with the first death in America reported today. There have been five confirmed cases in the UK, but all are said to be responding well to treatment.
While the potentially deadly infection has not reached Northern Ireland, health officials have stepped up their response to the threat of it spreading.
A new 24-hour hotline (0800 0514 142) for people worried about the flu will go live tomorrow while infection masks were distributed to A&E department across Northern Ireland today.
Posters offering guidance have been put up at transport hubs while advice leaflets will be delivered to every home in the country in the coming days.
Health minister Michael McGimpsey said the authorities had to prepare for the worst case scenario.
“We continue to maintain the strictest surveillance and monitoring here in Northern Ireland,” he said. “We have no cases confirmed here, although there are two cases currently under investigation.
“Northern Ireland has robust plans in place for dealing with situations like this. We have worked and are working extremely closely with the rest of the UK and the Republic of Ireland to ensure we are prepared and to ensure that the public is protected to the maximum level possible.”
Four tests carried out in the Republic so far have all proved negative.
PA