Call to mix vaccines for crucial second jab
A LEADING health official has called on the National Immunisation Advisory Committee to advise in favour of mixing vaccines to help increase the speed of the vaccination programme.
University College Cork immunovirologist Professor Liam Fanning also said combining doses has been shown to work internationally.
The latest advice from the National Immunisation Advisory Committee (NIAC), according to the HSE, has recommended against mixing vaccine doses, for example, following a first dose of AstraZeneca vaccine with a second dose of Pfizer vaccine.
However, a mixed-dose programme could have huge benefits for the recipients of the vaccine according to recent research in terms of increasing overall immunity for recipients against Covid-19.
This month the country is expected to receive a significant delivery of 844,000 Pfizer vaccines as question marks remain over the amount of AstraZeneca doses due.
Prof. Fanning told the Irish Mail on Sunday: ‘I would encourage those in NIAC to really consider using that data from recent trials to say those who have been vaccinated with AstraZeneca can now be vaccinated with an mRNA vaccine such as Moderna or Pfizer.
‘It seems that the new response to that heterologous challenge [mixed doses] is actually extremely strong, and perhaps even a little bit stronger than the double-Pfizer. The data has shown that mixing the vaccine type yields a very strong immune protective response.’
A recent study into heterologous Covid-19 vaccine programmes found a robust immune response in mice equal or greater than that of a homologous (single) vaccine programme.
Canada’s immunisation advisory body has also changed its view to allow those who had received a first dose of the AstraZeneca vaccine to receive either the Pfizer-BioNTech
or Moderna vaccines as their second dose. It also said that the Pfizer and Moderna vaccines could be used interchangeably, although it recommended sticking with a single brand when possible.
This guidance follows similar advice given in Denmark, Finland, France, Germany, Norway, Spain and Sweden.
As with Ireland, most of Canada’s vaccine shipments have been from Pfizer, while deliveries from AstraZeneca and Moderna have been smaller.
Around 62% of Canada’s population have received their first dose of vaccine while only a very small percentage is considered fully vaccinated. The country’s goal is to provide as broad a spectrum of the population with a certain amount of protection from the virus.
Prof. Fanning said: ‘Immunologically, there’s no reason why one wouldn’t give a heterologous vaccine challenge. The difficulty was from a regulatory perspective, so AstraZeneca applied for approval for its vaccine while Pfizer applied for its vaccine. No company is going to apply for its vaccine and another. The data is there.’
On Friday, Health Minister Stephen Donnelly announced the interval between the administration of the first and second dose of AstraZeneca will be reduced from 12 weeks to eight weeks on a phased basis, subject to vaccine supplies.
Those who are due a second dose of AstraZeneca over the coming fortnight under the existing 12-week schedule will receive it as planned.
‘I would encourage NIAC to consider that data’