The Covid certification system is based on science and will reduce the spread of the virus, Health Minister Robin Swann has told MLAs.
Mr Swann also said a single message on coronavirus from the Executive would be the one that is “heard strongest”, amid ongoing tensions between some parties on regulations.
The minister was briefing his scrutiny committee on pressures facing the health service over the winter months.
He said: “Make no mistake, we are facing into possibly the most difficult winter that our health and social care system has experienced, but we are not without hope.
“If we all play our part and do everything that we can to limit the spread of Covid-19 to protect our services we will get through it.”
Committee members asked Mr Swann about Northern Ireland’s new Covid certification system, through which people will be asked for proof of vaccination or a negative test result to gain entry to licensed venues.
The scheme, which began on Monday, has been criticised by First Minister Paul Givan as “politically-motivated”.
Mr Givan’s party, the DUP, has opposed mandatory Covid certification and its minsters voted against its introduction at a meeting of the Stormont Executive.
His party colleague, MLA Deborah Erskine, asked the health minister: “Covid passports have been billed as one of the tools to protect our hospitals and ease winter pressures.
“What detail and what specific scientific evidence was provided and how effective is the Covid vaccination certificate in stopping the spread of Covid?
“What has been the experience elsewhere in terms of cases? Has it reduced the cases? How have businesses been impacted?”
Mr Swann said scientific papers are available on his department’s website.
SDLP MLA Colin McGrath said: “The Covid certificates, we have a debate coming up in the chamber next week which is one of the occasions we will get to debate legislation before it is enforced.
“Last Monday, the first minister said the Covid certificates were a policy which was not based on evidence, that there was no equality impact assessment completed, no human rights or legal opinion sought.
“I am a supporter of Covid certificates. Can we just clear this up: is there scientific and medical evidence that Covid certificates will help?”
Mr Swann said: “It is not just about vaccinations, it is the negative lateral flow and the negative PCR. I am aware that there are anti-vaxxers who are trying to latch on to this to prove their point.
“The scientific evidence about reduction of spread for those who have been vaccinated or those who have previously been infected, there is a reduction in spread.
“There is also for those who are vaccinated less chance of serious infection should they become infected or go on to get serious disease.”
The minister was also asked about recent public comments by an MP about the Omicron variant.
This week DUP MP Sammy Wilson, explaining why he voted against new Covid regulations in Westminster, tweeted: “They are not proportionate to deal with the spread of the mild Omicron variant.”
Ulster Unionist MLA Alan Chambers said: “What is your message to the Northern Ireland public in response to recent comments from senior politicians who seem to have become experts in epidemiology, that this new variant is going to be a mild condition?”
Mr Swann said: “I have always said that a single message coming out of the Executive, coming out of this Health Committee, coming out of the Assembly to the general population is the one that was heard strongest.
“We retained the wearing of face coverings in Northern Ireland, where other parts of the UK moved away from them. They are now moving back to them, so I think we took the responsible decision.
“We had no differential of messaging from here but it is disappointing when you get it from elsewhere because there are those who take comfort in hearing that miscommunication.”
