Are there reasons to think mixing vaccines is dangerous?

post by Maxwell Peterson (maxwell-peterson) · 2021-06-03T22:36:35.588Z · LW · GW · No comments

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    8 CellBioGuy
    6 ChristianKl
    -12 Stuart Anderson
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I'm planning to get a Pfizer dose, two months after getting a J&J dose. Is there any reason to think this is unsafe? Also, are there good reasons to think it is safe, beyond my current stance of just "I don't see any reason why it would be dangerous"?

Answers

answer by [deleted] · 2021-06-04T00:33:59.426Z · LW(p) · GW(p)

Opposite.  Them getting to your immune system from slightly different 'directions' likely increases effectiveness slightly, especially for the adenoviral vector vaccines where vector immunity might be an issue.

answer by ChristianKl · 2021-06-03T23:26:52.447Z · LW(p) · GW(p)

Part of the risk of a any drug is that you might be alergic to any ingridient. If you take multiple different drugs with ingridients, there's a higher chance you increase the chance of being faced with an ingridient that you have a bad reaction towards. I don't think that's a huge concern in this case. 

One problem with taking the same vaccine multiple times is that your body might build defenses against ingridients in the vaccine besides the spike peptide which makes the second dose less effective. As far as I remember the Russian vaccine uses different virus vectors for the first and second dose to counteract this. 

Given the situation we have in Berlin where we have at the moment more AstraZeneca vaccine, I got AstraZeneca as the first shot. My doctor recommended the BioNTech vaccine for the second shot because it might increase protection against new strains like the South American one. While giving that recommendation my doctor didn't think there were any risks regarding mixing that were worth telling me about. 

I think the difference in risk are likely tiny between mixing and not mixing. I would expect that it's more likely that mixing is reducing risk then increasing risk.

answer by Stuart Anderson · 2021-06-04T06:05:35.661Z · LW(p) · GW(p)

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↑ comment by Maxwell Peterson (maxwell-peterson) · 2021-06-04T13:52:58.156Z · LW(p) · GW(p)

I agree in most cases, but here specifically, I’m worried that doctors are just going to follow CDC guidance and say something like “vaccine efficacy cannot be directly compared, and one J&J counts as fully vaccinated, so current guidelines say no, no more dose”. And it would cost my company around $500 to go to a doctor’s office and get their advice, which seems like a waste.

Also, I’d already signed up for the appointment before posting this question, planning to go! So the alternatives here were not “ask LW or ask my doctor”, but rather “ask LW or ask no one”. The advice here is better than the no-advice option I would have gone with if LW didn’t exist, or deleted this type of question.

Replies from: stuart-anderson
↑ comment by Stuart Anderson (stuart-anderson) · 2021-06-04T16:10:32.310Z · LW(p) · GW(p)

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Replies from: maxwell-peterson
↑ comment by Maxwell Peterson (maxwell-peterson) · 2021-06-04T16:38:59.908Z · LW(p) · GW(p)

Yup yup - I was wondering if there was some weird less-known but persuasive reason it might be dangerous, so thought I’d do a double-check here. Cheers!

↑ comment by mukashi (adrian-arellano-davin) · 2021-06-04T06:14:33.078Z · LW(p) · GW(p)

He is not asking to any random forum on the Internet, he is asking to a community of rationalists with many well-informed people about many different topics. 

Replies from: stuart-anderson
↑ comment by Stuart Anderson (stuart-anderson) · 2021-06-04T07:48:54.359Z · LW(p) · GW(p)

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Replies from: maxwell-peterson
↑ comment by Maxwell Peterson (maxwell-peterson) · 2021-06-04T14:05:02.106Z · LW(p) · GW(p)

I’ve wanted this additional dose for more than a month but didn’t want to take someone else’s dose, so I waited. It is my understanding that supply is no longer a limiting factor on vaccination rates. This is based on two things:

  1. There are many unfilled vaccine appointments around me.
  2. The cumulative-vaccinations-by-day graph is leveling off. In April in my state we had something like 3 to 4% of the total population being vaccinated each week - now that number is around 1%.

And extra doses at my local CVS are probably not going to make it to India or Mexico or Africa if I skip my appointment. The vague feeling I’ve got is that the logistical issues are difficult enough that pharmacies won’t be sending vaccines back, though this is just a feeling. So I decided that this is a pretty different situation and doesn’t match the feeling I had in April of “I don’t want to take anybody else’s appointment”. Some states are literally running million-dollar lotteries to try and get people to get it!

Replies from: stuart-anderson

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