European Commission President Ursula von der Leyen has said she "deeply regrets" mistakes that were made in the Commission's move to trigger Article 16 of the Northern Ireland Protocol on 29 January.
Speaking to the European Parliament, Ms von der Leyen said: "The bottom line is that mistakes were made in the process leading up to the decision and I deeply regret that. But in the end we got it right.
"I can reassure you that my commission will do its utmost to protect the peace of Northern Ireland, just as it has done throughout the entire Brexit process."
She also told MEPs that lessons had to be learned about the slow roll-out of vaccines in Europe, and admitted that the EU was late to authorise vaccines and too confident that orders would be delivered on time.
However, she strongly defended the EU’s decision to negotiate vaccine doses as one bloc, instead of individual member states going it alone.
"I cannot even imagine what would have happened if just a handful of big players, big member states had rushed to it and everyone else had been left empty-handed," she told MEPs.
"What would that have meant for our internal market and for the unity of Europe? In economic terms, it would have been nonsense and would have been the end of our community."
She also defended the authorisation process carried out by the European Medicines Agency.
"We have made a choice to not make any shortcuts when it comes to safety or efficacy. We fully defend that choice.
"There is no compromise possible when it is a matter of injecting a biologically active substance into an individual who is in good health," she said.
"This is why we rely on the EMA procedure, and yes, that means that approval takes three to four additional weeks. That additional time is an essential investment to establish confidence and ensure security."
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President von der Leyen said the vaccination campaign was picking up speed and momentum.
She said that since December 26 million doses had been delivered and more than 17 million people had been vaccinated.
"We're going to work as hard as we possibly can in order to meet our objective so that by the end of the summer at least 70% will have been vaccinated," she said.
Ms von der Leyen said science should be "rightly proud" of the achievement of producing vaccines.
She said it normally took five to ten years to produce vaccines.
"We did it in ten months. This is a huge scientific success and we should be rightly proud. But in a way science has outstripped manufacturing production," Ms von der Leyen said.
She told MEPs that a vaccine had some 400 ingredients and that production involved 100 companies. She said the commission had set up a task force to bring companies together to help ramp up production and remove bottlenecks.
"Industry has to match the groundbreaking pace in science," she said.
Ms von der Leyen said one bottleneck in production was linked to two synthetic molecules, adding: "If we had just 250g more of these molecules, companies say they could produce one million more doses of vaccines."
On the export transparency and authorisation mechanism, introduced on 29 January, President von der Leyen said there was no intention of restricting vaccine producers that were honouring their contracts to member states.
EU member states, members of the European Economic Area (EEA), the Western Balkans, and low and medium income countries were all exempt from the measure.
"Europe is always ready to help and we insist on our fair share," she said.
Fianna Fáil MEP Billy Kelleher said the Commission still needs to explain how the decision around Article 16 was reached.
Speaking on RTÉ's Today with Claire Byrne, he said "it is not the third secret of Fatima" and President von der Leyen should give a timeline of events surrounding the decision.
Mr Kelleher said he has tabled a parliamentary questions to the Commission and hoped to get some answers.
Separately, the Senior Director of Government Affairs and Policy for Johnson & Johnson's supply chain EMEA has said the company has not delivered its dossier to the European Medicines Agency yet, but hopes to do so by the end of this month.
Speaking on RTÉ's Morning Ireland, Dr Leisha Daly said the Johnson & Johnson vaccine is a "viral vector".
It works by using an inactivated common cold virus to take a piece of the genetic material of coronavirus into the human cell and this then activates the body's own immune system to fight against the virus.
The vaccine can be stored in normal refrigeration temperatures.
She said the three trials were completed at the end of last year and over 45,000 people participated in the study, with a significant cohort of these participants in South Africa.
The results found that over 85% had protection against severe disease and 100% against hospitalisation and death.
Of the South African group, Dr Daly said that 90% of participants had the variant first detected in South Africa and the vaccine was 57% effective in preventing severe disease and hospitalisation.