The National Immunisation Advisory Committee (NIAC) is expected to recommend the use of the Johnson & Johnson vaccine for those aged 50 and older in Ireland.

However, it could also be used for younger people if there is no option of another vaccine, and for those who live in hard to reach communities.

The NIAC advice will be considered by the Chief Medical Officer, Dr Tony Holohan.

He will give his view and advice on it to the Minister for Health.

The Government will then advise the Health Service Executive on how it should proceed with the vaccine.

Last week, the European Medicines Agency (EMA) said that the benefits of the Johnson & Johnson Covid-19 vaccine outweigh the risks.

Use of the company's one-dose vaccine was temporarily halted by US regulators after a small number of blood clots were reported.

Europe's drug regulator said it had found a possible link between Johnson & Johnson's Covid-19 vaccine and rare blood clotting issues in adults who had received the shot in the United States.

The EMA said its safety committee concluded that a warning about unusual blood clots with low blood platelets should be added to the vaccine's labels.

It said that it had taken into account all the currently available evidence, including eight reports from the US of serious cases of unusual blood clots. One had a fatal outcome.

NIAC said that it would meet and consider the recommendations and the evidence produced by the EMA, before making recommendations.

The Special Envoy on Covid for the World Health Organization has said that the expected decision by NIAC on the recommended use of the vaccine for those aged 50 and older "represents a real abundance of caution by the regulators".

Speaking on RTÉ's Drivetime, David Nabarro said he liked the fact that NIAC said it could be used for younger people if there is no other option.

"This is advice being given for a very, very rare side effect and the authorities are saying if there's no alternative, use it," he said.

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Paul Moynagh, Professor of Immunology at Maynooth University, said it is "good news" that the expected recommendation from NIAC in relation to the Johnson & Johnson vaccine is not as restrictive as for AstraZeneca.

The use of AstraZeneca is recommended for people above 60 years of age.

He said if the advice had been that only people over 60 could receive the J&J vaccine, there would be an excess of vaccines for that age group.

Mr Moynagh said NIAC was being overly cautious "in the sense that the EMA has indicated the benefits outweigh the risks sort of across all age groups", especially in a time when the level of transmission is very high.

"I would come to a different conclusion if there was a limitless supply of other vaccines available, but at this point in time we don't have a limitless supply," he said.

He said he imagined that this consideration formed part of the decision.

Professor Moynagh said the single-shot Johnson & Johnson vaccine "works really well".

He said there appears to be very rare clotting events associated with both of these vaccines.

"Some questions may arise as to why the distinction is being made between the two vaccines with respect to different age cohorts," he said.

However, he added that the vaccines are "very efficacious and also very safe".

Professor Kingston Mills, Immunologist at Trinity College Dublin, said he is "delighted" that the use of the Johnson & Johnson vaccine is expected to be recommended by NIAC. However, he said that he is "disappointed" that it is largely confined to those aged over 50.

"I think the risks of this vaccine are very small: eight cases of the rare blood clotting events among seven million people vaccinated in the States, compared with the risks of Covid-19," he told RTÉ's Claire Byrne Live.

Prof Mills said he hoped it was possible that the J&J vaccine would be offered to those aged over 60, but said he expected health officials had already calculated that there was enough AstraZeneca vaccines to vaccinate that group.

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