The go-ahead has been given for the mixing of Covid-19 vaccines, Health Minister Stephen Donnelly said today.

It means that people who received a first dose of AstraZeneca vaccine and did not opt for another can now get a second shot with either Pfizer or Moderna vaccines.

It also paves the way for an autumn and winter Covid-19 vaccination booster campaign although the final guidelines are still awaited from the National Immunisation Advisory Committee next week (Niac).

This would likely start in early October and the most vulnerable groups would be first in the queue to be offered both a flu and Covid-19 vaccine at the one time.

Mr Donnelly said today that he had received advice that “people who received one dose of AstraZeneca vaccine who decided not to get a second dose or were advised not to that we can now mix the vaccines.”

The over-60s in particular were very aggrieved that they were given no choice but to get an AstraZeneca vaccine although its efficacy was not as high as Pfizer or Moderna.

A significant number who got the first dose have held out and waited to get a Pfizer or Moderna vaccine as a second shot.

“My department will be working with the HSE to implement that as quickly as possible,” he said.

He said Niac has previously indicated it is likely to recommend a booster shot for the fully vaccinated this autumn and they are working out the priority groups.

It would mean people fully vaccinated, including those who received the one-shot Johnson and Johnson vaccine would be offered another jab to improve their defences.

The priority groups are expected to again be nursing home residents, the over-70s , people whose immune systems are compromised due to illness and healthcare workers.

He said Niac is “looking at the details of any potential booster campaign and I expect to receive details on that next week.”

The fact that it is allowing for vaccines to be mixed means that those who were fully vaccinated with AstraZeneca vaccine could be given a Pfizer or Moderna jab as a booster.

Germany and Israel have announced plans for booster-shot programmes, and a growing list of countries including the United Arab Emirates, China and Russia have already started administering extra doses.

Scientists remain divided on whether there is a need for a booster shot.

The World Health Organisation called for a moratorium on boosters until at least the end of September, pointing to poorer countries still struggling with the first stages of vaccination roll out.

Data from Israel indicated that the Pfizer vaccine’s effectiveness in preventing infection and serious illness wanes as time passes.

It is estimated that for people 60 and older, the effectiveness of the vaccine in preventing serious illness has dropped from 97pc 81pc.

Prof Eran Segal of the Weizmann Institute of Science said that 80pc “is still effective, but the gap is dramatic. Because if previously the chance of a vaccinated person aged 60+ getting seriously ill was 3pc, now it is 19pc, which means six times more.”