To boost and mix mRNA?
October 22, 2021 3:43 AM Subscribe
I know this is an obnoxiously first world problem. I know YANMD. But I'm wondering if anyone else has any thoughts more informed than my own about whether to add a Moderna as my booster, as opposed to a third Pfizer.
I am medically (and occupationally) eligible for a booster shot and it's been the required 6+ months since my second dose of Pfizer. Given my underlying health conditions, and how a case of long COVID resulting from even a mild infection could further impact my quality of life and (most critically) ongoing treatment options for my preexisting medical condition(s), like everyone else I'm anxious to seize any margin I can of greater efficacy/longevity of the booster dose.
Along those lines, I had originally been thinking if the option were available I would want a moderna booster. However, all the data on the superiority of Moderna for efficacy and/or longevity as both a booster and the main series is based on the full dose, and the messaging is very clear that the Moderna booster will be at half dose. (I do not medically qualify for a full-dose Moderna "third shot".)
I'm aware that half a Moderna dose is still 50mcg of mRNA to Pfizer's 30mcg, so there still might be some edge, but I've also seen it pointed out that when they compared a full dose Moderna booster to a full dose Pfizer booster in the study of mixing and matching, Moderna wasn't necessarily 3x as effective as Pfizer, so who knows if a half dose of Moderna might possibly be less optimal than a full dose Pfizer?
Assume for the sake of the question that I can access a half dose Moderna booster just as quickly and easily as a half dose Pfizer booster (I know the best shot is the most timely one). I don't have any heart issues and didn't have a terrible time with either of my Pfizer shots, regarding the risk of rare side effects.
I am medically (and occupationally) eligible for a booster shot and it's been the required 6+ months since my second dose of Pfizer. Given my underlying health conditions, and how a case of long COVID resulting from even a mild infection could further impact my quality of life and (most critically) ongoing treatment options for my preexisting medical condition(s), like everyone else I'm anxious to seize any margin I can of greater efficacy/longevity of the booster dose.
Along those lines, I had originally been thinking if the option were available I would want a moderna booster. However, all the data on the superiority of Moderna for efficacy and/or longevity as both a booster and the main series is based on the full dose, and the messaging is very clear that the Moderna booster will be at half dose. (I do not medically qualify for a full-dose Moderna "third shot".)
I'm aware that half a Moderna dose is still 50mcg of mRNA to Pfizer's 30mcg, so there still might be some edge, but I've also seen it pointed out that when they compared a full dose Moderna booster to a full dose Pfizer booster in the study of mixing and matching, Moderna wasn't necessarily 3x as effective as Pfizer, so who knows if a half dose of Moderna might possibly be less optimal than a full dose Pfizer?
Assume for the sake of the question that I can access a half dose Moderna booster just as quickly and easily as a half dose Pfizer booster (I know the best shot is the most timely one). I don't have any heart issues and didn't have a terrible time with either of my Pfizer shots, regarding the risk of rare side effects.
The half dose thing is new to me. But absent that wrinkle, my gut would be to go for the Moderna.
A sweeping generalisation here, mixing was much better than getting the same dose, except for Moderna. If you had had two doses of Moderna and you get Moderna on top, that would give you a very good antibody response. But with Pfizer and Astra, mixing the dose after your first dose got you your best result, and it really coalesced around mRNAs as your third dose. (link to CoronaCast podcast- transcript available)
posted by freethefeet at 3:57 AM on October 22, 2021 [4 favorites]
A sweeping generalisation here, mixing was much better than getting the same dose, except for Moderna. If you had had two doses of Moderna and you get Moderna on top, that would give you a very good antibody response. But with Pfizer and Astra, mixing the dose after your first dose got you your best result, and it really coalesced around mRNAs as your third dose. (link to CoronaCast podcast- transcript available)
posted by freethefeet at 3:57 AM on October 22, 2021 [4 favorites]
Best answer: Epidemiologist here, but I am not your doctor. My assessment is that it's ideal to stick to continuing the series you've begun, if possible, but if both Pfizer and Moderna are available it is *functionally* immaterial which one you get as a booster. From an individual standpoint, there's no way to anticipate the robustness of your immune response to either but there are principles by which either would confer immunogenic benefit. The same can be said of safety concerns—they are exceedingly slim for whichever approach you take. From a population/epidemiological standpoint, getting *any* vaccine, on any dose and booster regimen, is doing your part.
posted by late afternoon dreaming hotel at 4:07 AM on October 22, 2021 [8 favorites]
posted by late afternoon dreaming hotel at 4:07 AM on October 22, 2021 [8 favorites]
Dr. Katelyn Jetelina addressed this in her blog (Your Local Epidemiologist) yesterday. Here is her post on a recent study about mixing vaccines.
posted by rakaidan at 4:07 AM on October 22, 2021 [4 favorites]
posted by rakaidan at 4:07 AM on October 22, 2021 [4 favorites]
Response by poster: Dr. Katelyn Jetelina addressed this in her blog (Your Local Epidemiologist) yesterday.
Thank you-- I thought this was the same post of hers I had linked above because it contains a lot of the same study info, verbatim.
posted by these are my travel socks at 4:10 AM on October 22, 2021
Thank you-- I thought this was the same post of hers I had linked above because it contains a lot of the same study info, verbatim.
posted by these are my travel socks at 4:10 AM on October 22, 2021
Due to supply issues - a vast number of vaccinated people in Canada (or Ontario at least) have mixes - I am an AstraModerna guy - the rest of the household family is Pfizer/Moderna. I don't have any auto-immune issues - however, I have weak lungs from childhood issues - if I get an average cold, it typically turns into bronchitis or (once every 4-5 years) walking pneumonia.
However - I am at the point that any vaccine and any booster is better than none. But this is just my opinion and I am not a medical professional.
Chances are high that this won't be the last booster - as this is still a 'novel virus', we will all likely need on-going boosters every 8 months for the forseeable future.
posted by rozcakj at 6:04 AM on October 22, 2021
However - I am at the point that any vaccine and any booster is better than none. But this is just my opinion and I am not a medical professional.
Chances are high that this won't be the last booster - as this is still a 'novel virus', we will all likely need on-going boosters every 8 months for the forseeable future.
posted by rozcakj at 6:04 AM on October 22, 2021
Best answer: I'm a doctor.
1) Homologous vs heterogenous booster vaccination regimens
Not complicated
HOM = 3rd shot same as shots 1 and 2
HET = 3rd shot different than 1 and 2
NB: shots 1 and 2 = Primary vaccination regimen (PRI)
2) What do we know about whether one regime is better than the other?
Nothing definitive, though two studies out this week--a major one from Israel with 12000 participants, and a smaller one from Switzerland (I think)--found HET was about 30% more effective against the Delta and Beta (don't ask) variants of Covid.
In Israel's turgid words:
The fold increases from baseline in both binding and neutralizing antibody titers were similar or greater after heterologous boosts compared to homologous boosts
and
this preliminary report demonstrates that boosting with any of the three vaccines currently licensed or authorized for emergency use in the US will stimulate an anamnestic response* in persons who previously received of the primary series of any of these vaccines. Homologous boosts provided a wide range of immunogenicity responses, with heterologous boosts providing comparable or higher titers
That said:
In these two studies, as well as every other one I'm aware of, both HET and HOM regimens boosted immunity regardless of PRI regimen
In other words, just get a 3rd shot
*With infection and with vaccination, one has a peak immune response in the weeks after antigen exposure, then a natural decay over months to years. This is 100% normal and to be expected. Following this decline in immunity, the immune system responds more rapidly and strongly when exposed to the antigen again. That's what anamenestic means--hence the logic of booster vaccinations
posted by BadgerDoctor at 6:09 AM on October 22, 2021 [5 favorites]
1) Homologous vs heterogenous booster vaccination regimens
Not complicated
HOM = 3rd shot same as shots 1 and 2
HET = 3rd shot different than 1 and 2
NB: shots 1 and 2 = Primary vaccination regimen (PRI)
2) What do we know about whether one regime is better than the other?
Nothing definitive, though two studies out this week--a major one from Israel with 12000 participants, and a smaller one from Switzerland (I think)--found HET was about 30% more effective against the Delta and Beta (don't ask) variants of Covid.
In Israel's turgid words:
The fold increases from baseline in both binding and neutralizing antibody titers were similar or greater after heterologous boosts compared to homologous boosts
and
this preliminary report demonstrates that boosting with any of the three vaccines currently licensed or authorized for emergency use in the US will stimulate an anamnestic response* in persons who previously received of the primary series of any of these vaccines. Homologous boosts provided a wide range of immunogenicity responses, with heterologous boosts providing comparable or higher titers
That said:
In these two studies, as well as every other one I'm aware of, both HET and HOM regimens boosted immunity regardless of PRI regimen
In other words, just get a 3rd shot
*With infection and with vaccination, one has a peak immune response in the weeks after antigen exposure, then a natural decay over months to years. This is 100% normal and to be expected. Following this decline in immunity, the immune system responds more rapidly and strongly when exposed to the antigen again. That's what anamenestic means--hence the logic of booster vaccinations
posted by BadgerDoctor at 6:09 AM on October 22, 2021 [5 favorites]
I get my Covid info from the weekly "clinical updates" by Dr. Daniel Griffen on Microbe.tv. He reported on what I assume was the same study that mixed vaccines showed a bit better response but also noted that the connection between antibody levels and immune protection is completely unknown. For example, the J&J vaccine produces antibody levels much lower than the RMA vaccines, but still provides decent protection.
Interestingly, his host, Dr. Vincent Racaniello (Ph.D college professor) thinks the case for boosters is weak because although your protection against getting sick may go down with time, the protection against getting seriously ill and hospitalized stays strong.
posted by SemiSalt at 6:22 AM on October 22, 2021
Interestingly, his host, Dr. Vincent Racaniello (Ph.D college professor) thinks the case for boosters is weak because although your protection against getting sick may go down with time, the protection against getting seriously ill and hospitalized stays strong.
posted by SemiSalt at 6:22 AM on October 22, 2021
Can't answer to your specific question but my first shot was Pfizer and second Moderna (I'm in Ontario). From a side-effect issue there was no difference to me. Both gave me a sore arm for about 2 hours with no other ill issues.
posted by dobbs at 8:01 AM on October 22, 2021
posted by dobbs at 8:01 AM on October 22, 2021
My impression is that the clinical case for mixing is murky at best, but that may change.
One practical reason to stick with the same vaccine is international travel. As countries establish vaccine requirements that include booster for visitors (Israel has already done this), the choice least likely to cause trouble will be to do the least "clever" and most "conventional" thing.
That is undoubtedly three doses of the same vaccine. It's totally possible that countries will say "three of anything approved by the WHO in any combination is fine, go nuts!". But it's also possible that the particular country you want to visit in a couple of years will say "three doses of the same vaccine". It's very unlikely they'll say "two doses of one vaccine and one of another".
posted by caek at 1:50 PM on October 22, 2021 [1 favorite]
One practical reason to stick with the same vaccine is international travel. As countries establish vaccine requirements that include booster for visitors (Israel has already done this), the choice least likely to cause trouble will be to do the least "clever" and most "conventional" thing.
That is undoubtedly three doses of the same vaccine. It's totally possible that countries will say "three of anything approved by the WHO in any combination is fine, go nuts!". But it's also possible that the particular country you want to visit in a couple of years will say "three doses of the same vaccine". It's very unlikely they'll say "two doses of one vaccine and one of another".
posted by caek at 1:50 PM on October 22, 2021 [1 favorite]
Roger that caek. I recently travelled abroad as a J&J/Pfizer recipient (1 dose each). And while I didn't get blocked anywhere, I had to explain the situation to a customs officer and he was very perplexed by the situation. If the line behind us hadn't been so long, he might have made it an issue but after some furrowed eyebrows waved us through. It could easily have gone differently.
posted by sjswitzer at 6:45 PM on October 22, 2021
posted by sjswitzer at 6:45 PM on October 22, 2021
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posted by these are my travel socks at 3:53 AM on October 22, 2021