Thousands of vaccinations that were to take place today using the AstraZeneca vaccine, must now be rearranged, as a result of new advice from the National Immunisation Advisory Committee (NIAC).

The NIAC insists that "all authorised COVID-19 vaccines are highly effective in preventing hopitalisation, severe illness and death". However, it said it has changed its advice on the use of the AstraZeneca vaccine "in light of the outcome of the recent investigation by the Europeans Medicines Agency (EMA)".

Following this investigation, the EMA has added a new rare side-effect to the vaccine's product information - unusual clotting events with low platelet counts. Such an event is estimated to occur between four and 10 in every one million people, one of whom may die.

As a result of this, the NIAC has recommended that the AstraZeneca vaccine should not be used on people under the age of 60, including those with medical conditions and high, or very high risk of severe COVID disease.

It also recommended that a second dose should not be given to anyone who developed unusual blood clots with low platelets after the first dose.

The advice for those who have already received a first dose of this vaccine is as follows:
-Those aged 60 and older should receive their second dose 12 weeks later as scheduled
-Those aged under 60 years with a very high risk or high-risk medical condition should receive their second dose 12 weeks later as scheduled
-Those aged under 60 years without a very high risk or high-risk medical condition should have the scheduled interval between doses extended to 16 weeks to allow further assessment of the benefits and risks as more evidence becomes available.

According to the NIAC chairperson, Prof Karina Butler, all the authorised COVID-19 vaccines, including the Astra Zeneca vaccine, "are highly effective in preventing hospitalisation and severe COVID-19 disease.

"NIAC realises the need to balance the significant benefits of a national vaccination programme with the very rare risk of these reported events. While this is an extremely rare condition, consideration must be given to the fact that it has a very high risk of death or severe outcome. As the risk/benefits of Vaxzevria COVID-19 AstraZeneca vaccine may vary by age and as alternative COVID-19 vaccines are available NIAC has revised the recommendations for use of this vaccine," she explained.

She added that the NIAC strongly encourages everyone "to accept the COVID-19 vaccine they are offered".

Responding to the new advice, the acting chief medical officer, Dr Ronan Glynn, said that he was "hopeful" that this would not have a significant impact on the vaccine rollout, although he acknowledged he could not say that "with absolute certainty".

As a result of this advice, which was issued on Monday evening, the HSE has cancelled all AstraZeneca vaccination clinics planned for today. These will now have to be rearranged.