Q&A: What’s changed with Covid-19 vaccines and will it cause delays?

State health officials have decided not to give the Covid-19 vaccine regarded as a "game-changer" in the fight against the virus – the Oxford-AstraZeneca jab – to people aged over 70.

Insufficient data on the effectiveness of the virus on older people has led the Government to follow Germany, Austria and other countries which have opted not to use the considerably cheaper and easier-to-administer vaccine on that age cohort.

What does this mean for the Government’s plan to vaccinate the population?

It means it has to be reworked and this work is now being carried out. Vaccinators are, at the moment, inoculating the first two groups in the State’s priority queue: older people and staff in nursing homes and other care facilities, and frontline healthcare workers. The next group to be vaccinated are the almost 500,000 people aged over 70, starting with those aged over 85. The plan is that they will start receiving their vaccines in the middle of this month.

If they cannot receive the AstraZeneca vaccine, which ones will they get?

There are two other vaccines authorised for use and being administered in Ireland: the Pfizer/BioNTech and Moderna vaccines. These are the mRNA vaccines that use a bit of genetic code to cause an immune response that fights off the virus. They are complicated to manage, requiring storage at extremely low temperatures and defrosting before use with a limited life afterwards.

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In contrast, the Oxford-AstraZeneca vaccine uses a harmless virus that is altered to look a lot more like the coronavirus and can be stored in a fridge and administered by a pharmacist or GP.

Are there enough Pfizer and Moderna vaccines to vaccinate the over-70s on schedule?

This is what the Health Service Executive and the State’s vaccine taskforce are assessing. The aim was to vaccinate this group before the end of March but this was based on 600,000 AstraZeneca vaccines being delivered during that time and being available to the over-70s.

HSE chief executive Paul Reid said the plan was to receive 40,000 Pfizer vaccines and 10,000 Moderna vaccines every week but that the health service was expecting extra deliveries of these during February. However, the HSE was still trying to figure out whether all people over 70 would be vaccinated as planned by the end of March.

Tánaiste Leo Varadkar said the rollout for the over 70s "may well be slower", and faster for healthcare workers and other groups.

Can Pfizer and Moderna vaccines be saved for the older people, while younger people receive the AstraZeneca jab?

This is one suggestion that has been made. The Irish Pharmacy Union said the AstraZeneca vaccines should be used on any remaining healthcare workers and that GPs should instead be given all the Pfizer and Moderna vaccines being used in hospitals to vaccinate the over-70s.

This proposal effectively creates a new “AstraZeneca” queue with some swamping of the priority groups. The HSE has said that, as a result of the AstraZeneca recommendation for older people, other age cohorts could be vaccinated at the same time as the over-70s.

Which vaccine is the best?

All three have been deemed very effective at reducing severe disease in people who contract Covid-19; it is just there is insufficient data on how much the AstraZeneca vaccine protects people aged over 65. Overall, the vaccine was found to be 62 per cent effective in trials. This compares with 95 per cent and 94 per cent respectively for Pfizer/BioNTech and Modern vaccines after two doses.

Are there any circumstances in which the AstraZeneca vaccine will be given to the over-70s?

This depends on whether there are shortages of other vaccines. Prof Karina Butler, chair of the National Immunisation Advisory Committee, said this is possible; if there were going to be significant delays, then the best vaccine would be "the one that is available to you".