Covid Vaccine Mixing

[GuitarStv]

Thought this article might be of interest to this discussion:

https://www.bbc.com/news/health-57636356

There's no new information there.

The preliminary results of the Com-Cov study (https://www.sciencedirect.com/science/article/pii/S0140673621011156) were already discussed in this conversation.  It's a small collection of preliminary data that looks promising as far as safety and efficacy goes for mixing AZ and Pfizer.  It shows that reactions after the first dose were worse when mixing AZ with Pfizer, than with two shots of Pfizer.  Promising initial data, but we're still waiting for the full results with the larger group under study to come in.  When it does, we'll know if the educated guess we're making on the preliminary data was correct.

As was previously mentioned, this study doesn't compare mixing Pfizer and Moderna and it doesn't compare mixing Astra Zeneca and Moderna.  Those are still applications without preliminary data.  When we get data for these uses, we'll know if that bet was also correct.

[GuitarStv]

With all due respect there is new data in the BBC article (from the preprint): immunogenicity of varying prime / booster combos (only AZ / Pfizer) vs just the reactogenicity / safety information of your Science Direct link.

Are you talking about the preliminary, pre-publication data from here: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3874014?

That data was released earlier, and discussed (and, from everything I can tell is why Canada decided to go whole hog into mixing vaccines).  Unless I am missing something?

[Sibley]

Haven't seen any discussion of it here, but I have seen that people who got J&J may want to get a dose of one Pfiser or Moderna. I got J&J back in early April, and am seeing my doctor this week for regular asthma meds. I plan to ask if I should get something else. If the doctor says yes, and they have any there, I may just get it then.

[elaine amj]

And if someone is hesitant about mixing and feels the risks of mixing is higher than the risks of waiting, they can wait. We are very fortunate in Canada that we have a ton of vaccines coming in over the next month.

DS got Pfizer first and when he became eligible for his second shot, the only available option (due to his availability) was to line up at a popup clinic for Moderna. I was a bit hesitant about that primarily because we travel to Asia and it's just hard to say what some countries will accept/not accept (I have less concerns about North America/Europe).

Anyway, his risk factors are low - he is 18 and was just about to leave home to spend a year working at a summer camp with kids. Everyone at camp has to have a PCR test before arrival and then get a rapid test upon arrival. Most importantly, we will not be exposed to him (the rest of us have high risk factors). And even if we do get to visit him on an off-day, the rest of us are all fully vaxxed, which again reduces our risks considerably. 

Due to all that, I decided he is OK with one dose for now and can just wait another month until end of July/early August when Canada will be flooded with Pfizer.

If he was still living at home, the risks would change and I would have likely advocated mixing with Moderna simply so DS wouldn't have to stay locked down for an extra month to protect the rest of us.

Plus frankly, it's been a giant relief to worry less. And so very very very nice to see people again. That's worth quite a bit of risk in vaccine mixing IMO.

And for anyone who works in places with high exposure or lives in a large congregate setting or has people in their lives with higher risk factors, especially with delta making its rounds (as it is in Ontario), I'd seriously consider vaccine mixing worth the risk.

I have a friend who wants to wait and see with the vaccine. She just wants to let the rest of us test it out for her for a while longer. To protect their family, she keeps them mostly isolated. That's her choice for now. For us, we are loving the extra freedom and relief being vaccinated earlier is giving us. Especially now that things are opening up in Ontario.

Sent from my VCE-AL00 using Tapatalk

[RetiredAt63]

The extra freedom and relief are so worth it!   Enjoy!

Now that I am fully vaccinated I was able to visit DD and meet my granddaughter.   Ottawa is doing really well with vaccination rates.

[Sibley]

Haven't seen any discussion of it here, but I have seen that people who got J&J may want to get a dose of one Pfiser or Moderna. I got J&J back in early April, and am seeing my doctor this week for regular asthma meds. I plan to ask if I should get something else. If the doctor says yes, and they have any there, I may just get it then.

Well, doctor is going based on CDC recommendations, and she didn't see one for that. So I don't have to get poked.

[electriceagle]

The vaccines will work fine -- the problem might be with travel.

With so many countries requiring vaccination as a condition of entry, you want to have had a vaccination regime that is written down on the piece of paper that the immigration official was given. Mixing vaccines might cause confusion.

[TrMama]

The vaccines will work fine -- the problem might be with travel.

With so many countries requiring vaccination as a condition of entry, you want to have had a vaccination regime that is written down on the piece of paper that the immigration official was given. Mixing vaccines might cause confusion.

I've had mixed doses (AZ and Moderna). I have zero concerns about travel. I fully expect the countries who're currently making an issue of this to eventually accept mixed dose travelers. I mean, many of the world's influential politicians were very publicly immunized with mixed doses. Are the Trudeau's and Merkels of the world just going to stay home forever? I doubt it.

In the moment, and now, I was much more concerned with protecting myself from an awful disease than I was about which countries I might go on vacation to in the future.

For what my antedata is worth, I was much less sick after my Moderna booster than the initial AZ dose. I was still too sick to work the day after, but after a Gravol induced morning nap I was feeling pretty normal by 3pm.

[habanero]

Pfizer recommends its second dose after 21 days, Moderna recommends a 28-day interval, and AstraZeneca has recommendations were for a second shot between four and 12 weeks after the first.  Canada's guidance thus far has been that anything under four months between vaccines is fine (https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/rapid-response-extended-dose-intervals-covid-19-vaccines-early-rollout-population-protection.html) - although how they made that determination without actual data is anyone's guess.  As far as delays go, the preliminary studies I've read regarding mixing AZ with Pfizer and showing efficacy were done with both 8 week and 12 week delays between the shots, so at least I'm within that range.  Part of the problem with using these vaccines outside of the known/tested recommendations is that we can't really say with any confidence what the correct protocols are for distribution.  Hopefully in a couple months we'll get confirmation that this guess was indeed correct.

Due to a wish to get more 1st doses here (Norway) the interval was extended to 6 weeks, then 12 (in my case). Will most likely be 9 or 10 in the end due to increased supply. Our health folks pointed out that the official guidelines or 3 (or 4) weeks is due to what was used in the trials. And 3 weeks were used not because it was assumed optimal but because it was the shortest interval allowed and they wanted results as soon as possible.

If they had a lot more time on their hands they would probably experiment with various period to see which (if any) was deemed most efficient.

If you have had confirmed covid here you only need 1 shot to be considered fully vaccinated and I think you have to wait 3 months since confirmed infection before you can get that shot.

We have ditched AZ completely (6 deaths in ~140k doses) so everyone who got AZ first got mRNA second, there is no option to get AZ second time. J&J we never started using, you can in theory get it if you want/need to outside the regular queue but it's borderline impossible in practise. Apparently our side effect monitoring is top notch  (ref the number of AZ deaths here compared to most other places, and the problems with AZ were pretty much discovered here and in Denmark first) and so far there has been no reports of any problems mixing. While its not a study per se its a pretty large sample closely monitored. On the the other hand due to the vaccination strategy AZ was predominantly given to younger cohorts in health care jobs as the >65y and at-risk-groups were mostly already started on Pfizer which we got first.