Reading this story in the NYTimes about some Germans rejecting the Astra-Zeneca vaccine because they’d rather get the Pfizer/BioNTech got me curious.
Is it possible (and/or possibly beneficial, or at least not harmful) to get vaccinated with say, the Moderna vaccine today and then later get the Astra-Zeneca (e.g.) vaccine?
I can see a scenario where an individual really would prefer to get Vaccine Y but when it’s their turn only Vaccine X is available so they get it. Then, later when their preferred Vaccine Y is available they get that vaccine, too.
Is that OK? Is it dangerous? Is it a good idea? Etc.?
Obviously there’s no data, because why would anyone devote limited resources to studying this.
Is there any a priori reason to think there’s a lot of risk for a normal healthy person? No. But it’s an unknown, and I think it would be foolish to take an unknown and unnecessary risk unless there’s some clear benefit. The obvious scenario would be if it’s shown conclusively that the vaccine that you have already taken is ineffective against a widely circulating variant, whereas another available vaccine is effective. In that scenario I’d definitely take the second vaccine, and I’m sure there would be official advice issued to do so.
(All of the above assuming unlimited supply of vaccine, considerations of who should be prioritized come into play in the real world of course.)
Presumably the different vaccines are, well, different and have some different mechanism for achieving immunity. If so then one of each will not be as effective as both of one of them.
If mixing vaccines was better I would think that is what doctors would give us. But they don’t and almost certainly for good reason.
Right now it looks like there is a very good chance people will need to do regular booster shots (similar to the annual flu shots). So in a year or whatever you are probably going to get another shot anyway.
I was just thinking about this reading the Times article I linked above. I’m thinking there are people who will want to do this because they’re not happy with what was offered to them but didn’t want to risk getting nothing at all so they took it anyway.
Someone might figure:
“Well the AZ shot is only 70% effective (or whatever) but that’s all they had. I wish I could have gotten the Pfizer shot that’s 95% effective (or whatever). I’ll get the AZ right now then later, if I can, I’ll get the Pfizer shots for that ‘extra 25%’ protection.’”
The conclusion that they’d be getting an ‘extra 25%’ protection’ is probably not that simple or accurate but I wonder if they would be correct in assuming that there would be at least some benefit to this.
Consider the hypothetical:
Vax A is 40% effective while Vax B is 98% effective.
Vax B is not available to you; you can have Vax A or nothing
You get the Vax A treatment.
Later Vax B becomes available. There is enough for everyone else. Do you get the shot?
That’s sort of the way I was thinking about this–Like a booster shot to give you that added X% protection. Especially if you are particularly vulnerable.
Yes but the idea is not that you get twice the protection or whatever, just that after taking the second, preferred treatment, you are now getting a higher degree or protection than you would have with just the original shot.
Mixing the vaccines would not be the goal. FOR ONE THING IT’S WASTEFUL. Were it possible the “double-vaxxer” would likely just as soon have the first, non-preferred shot magically disappeared.
I think any vaccine, approved in the U.S., would have been shown to be just about 100 percent effective against hospitalization and death. So getting Y later seems unlikely to be worthwhile unless it is some sort of annual booster.
In May, results should come in from J&J’s 2-shot regimen. If much more effective than the single shot at preventing milder illness, maybe a second J&J jab will be recommended for high-risk people who got the first.
Most adult Americans are not up to date on all non-COVID vaccines. Rather than looking for another COVID jab, some should be asking when they last got the one that includes whooping cough.
Last I’ve heard they are studying it, including mixing the 2 dose regiment with different vaccines. It is simply too early to tell, and the studies to approve the current vaccines were done under such controlled circumstances that data outside those conditions are not yet known, but there is some indication that mixing and matching may provide better protection, but such limited data. So if you mix and match, or get the shots further part of closer together then the suggestion they generally say it’s assumed safe, but we are not going to talk about effectiveness. For example originally the Moderna vaccine only gave IIRC a 3 day window of the second shot, outside of that they still suggest taking it, but they say they can not confirm the 95% level if you do. I think that has eased to something like 3-6 weeks after is still OK.
A UK trial has been launched to see if giving people different Covid vaccines for their first and second doses works as well as the current approach of using the same type of vaccine twice.
The idea is to provide more flexibility with vaccine rollout and help deal with any potential disruption to supplies…
…While this study was initially designed to provide greater flexibility for vaccine rollouts, there is the tantalising possibility that mixing vaccines could provide even better, longer-lasting protection.
The story also states that some regimes of vaccination against Ebola use two different vaccines in order to improve protection, so this is some sort of precedent.