> Just pick the kids who are healthier, and call them "eligible".
Sure, yeah. Or whatever. But there's no evidence for that in the article, it says it was done based on age, and then matched between comparable communities. You'd have to not only mess with the eligibility, but only do so in the vaccinated communities. Because they compared eligible and ineligible children in the unvaccinated communities, too. And again, the cohorts were split apart by age. Maybe a bunch of unhealthy children didn't get the vaccine for that reason, but they'd be included in the age-cohort anyway.
Of course they could maliciously juice the study but the "what if richer, healthier children were the ones that got the vaccine" just doesn't seem a reasonable criticism at least as described. It seems like a perfectly good design to avoid being confounded that sort of thing.
> You'd have to not only mess with the eligibility, but only do so in the vaccinated communities. Because they compared eligible and ineligible children in the unvaccinated communities, too.
Yes, I get that. I'm not suggesting malfeasance here [1]. I'm just saying controls are hard, and these problems pop up in the best studies.
The difference between the clinical trials and this was that the clinical trials were an actual RCT, and this is an observational study. Observational studies almost always have confounding issues.
[1] I do think the immortal time bias is real, however. Whether or not the bias was consistent between groups is a separate question, but I almost don't really care. The fact that they're reporting that older children survive a bit longer than younger children, and not mentioning this issue, is sketchy to me. They either don't understand the problem (bad), or are exaggerating (typical, but still bad), or they're hiding something (really bad).
Honestly stuff like this just makes me exhausted for the state of medical science. You spent a crapload of money on this. Immortal time bias is confounding 101. We know how to avoid it. Do the damned RCT!
> Kids who make it to age N are more likely to survive to age N+1 than kids who make it to age N-1
Look, maybe I'm just giving them credit because this is filtered through journalism, but isn't that the point of the control communities? You can subtract out this bias using the control community. It's all down to picking comparable controls, obviously. If I had to point to a place you could screw up it would be picking the wrong control communities. Ideally you'd probably pair communities and then assign them at random to get the vaccines or not.
I'm not objecting to the idea that there could be confounders, just that it's probably not sampling bias along the lines of "richer and healthier children probably got the vaccine." If all you're saying is, "it's not an RCT" then... yeah, it's not?
The question is how hard is to pick good control communities. During the pandemic I've read a lot of preprints about cures for covid-19 (like Ivermectin) and many of them used a similar aproach. It looks very hard. I've seen too many bad results with this kind of controls. Double blind randomized controled trial or it didn't happen.
We already did the RCT and saw that the incidence of severe malaria was reduced.
Now we've done an actual rollout, and have seen in observational data a bigger reduction in all-cause mortality than we expected. It's relatively high quality observational data, but of course the risk of confounds is larger than the RCT.
Sure, yeah. Or whatever. But there's no evidence for that in the article, it says it was done based on age, and then matched between comparable communities. You'd have to not only mess with the eligibility, but only do so in the vaccinated communities. Because they compared eligible and ineligible children in the unvaccinated communities, too. And again, the cohorts were split apart by age. Maybe a bunch of unhealthy children didn't get the vaccine for that reason, but they'd be included in the age-cohort anyway.
Of course they could maliciously juice the study but the "what if richer, healthier children were the ones that got the vaccine" just doesn't seem a reasonable criticism at least as described. It seems like a perfectly good design to avoid being confounded that sort of thing.