Can vaccines be mixed?

[Newnamefor2021]

My immediate reaction is no, but just wondering if that's the case?

There seems to be a urgent news conference scheduled at 3 regarding the Oxford vaccine. No regrets, I had my first one, it was a risk I was willing to take. I'm 37.

However, just mussing if that means a whole new vaccine or another type as the booster? I mean if we are going to have them every 6 months or so as was previously suggested I assume we just have what's available rather than one type for life?

The Oxford vaccine was never going to work as a booster anyway as existing antibodies against the adenovirus vector would massively reduce efficacy (this is why they used a chimp virus instead of a human virus).

So it's ok to mix? That's good to know.

Currently the Regulator has not authorised mixing vaccines for first and second dose, so no, it’s not okay.

I don’t think anyone knows yet though I believe there are currently trials being undertaken.

Ok, thanks everyone.

I imagine the news conference will enlighten us further what the strategy will be for those who have already had a first dose of AZ, if they decided to limit its use in younger people.

As already mentioned trials of mixing vaccines are ongoing. As of now the advice is to have the 2nd dose the same as the first, IF AT ALL POSSIBLE. That implies that in some circumstances a second dose of a different vaccine would be given, as that is preferable to none at all if the first one was not available.

This is still a new situation, with further information coming to light all the time. Policies change in response to new information, which is right and proper.

@PuzzledObserver trials for mixing vaccines are currently only for the same type of vaccine - e.g mixing AZ vax with Sputnik V. They are both “traditional” vaccines. There is some speculation that it might also be possible to mix mRNA vaccines (e.g. Pfizer and Moderna). I don’t know of any trials mixing a traditional vax with an mRNA vax. Do you?

The MHRA has not currently authorised any mixing of different vaxes. Today’s update will be interesting, but I would be very surprised if they authorised folks having had first AZ dose being given second doses of Pfizer or Moderna. Currently only one “traditional” vax (AZ/Oxford) and two mRNA vaxxes (Pfizer and Moderna) are authorised for use in the UK.

I think more likely than authorising mixing of vaxxes MHRA will either recommend continuing as before, or recommend a longer delay in AZ second doses for younger people, given that their risk from the virus is lower anyway, while further research is ongoing. I’ll also be interested in what they say about first doses.

[quote FatAnneTheDealer]@PuzzledObserver trials for mixing vaccines are currently only for the same type of vaccine - e.g mixing AZ vax with Sputnik V. They are both “traditional” vaccines. There is some speculation that it might also be possible to mix mRNA vaccines (e.g. Pfizer and Moderna). I don’t know of any trials mixing a traditional vax with an mRNA vax. Do you?

The MHRA has not currently authorised any mixing of different vaxes. Today’s update will be interesting, but I would be very surprised if they authorised folks having had first AZ dose being given second doses of Pfizer or Moderna. Currently only one “traditional” vax (AZ/Oxford) and two mRNA vaxxes (Pfizer and Moderna) are authorised for use in the UK.

I think more likely than authorising mixing of vaxxes MHRA will either recommend continuing as before, or recommend a longer delay in AZ second doses for younger people, given that their risk from the virus is lower anyway, while further research is ongoing. I’ll also be interested in what they say about first doses.[/quote]
Astrazeneca isn't a traditional vaccine (even if you put it in quote marks) - the only other adenovirus vector vaccine that's been approved before is the very recent Ebola vaccine.

@FatAnneTheDealer

I don’t know of any trials mixing a traditional vax with an mRNA vax. Do you?

No, I don’t. I knew there were trials starting, but haven’t followed the detail.

@PuzzledObserver I am pretty sure there aren’t any.

Well it looks like the advice at present is to go ahead and have your second jab. Under 30's with no health conditions which put them at increased risk (from Covid) are going to be offered Pfizer or Moderna in preference to AZ.

There is a trial combining Oxford AZ with Pfizer going on now.

www.nihr.ac.uk/news/worlds-first-covid-19-vaccine-alternating-dose-study-launches-in-uk/26773