The most important trend (IMHO) they point out is that effectiveness vs. severe disease does not drop or barely drops. They claim:
To date, none of these studies has provided credible evidence of substantially declining protection against severe disease, even when there appear to be declines over time in vaccine efficacy against symptomatic disease.However, the graph they provide doesn't seem to be based on data that appears reasonably chosen (that could be my limitaiton, sure).
They refer to appendices (which are here: https://www.thelancet.com/cms/10.1016/S0140-6736(21)02046-8/...), and specifically table S4 appears to be the basis for their graph D. In it, they split same-paper sources into early vs. late effectiveness with respect to hospitalization. Four sources are relevant.
- #5: Health IM of. Two dose vaccination data. 2021. 2021 - I can't find this source.
- #41 https://pubmed.ncbi.nlm.nih.gov/34401884/ - ...but this paper has huge error bars and additionally the average effectiveness jumps up and down just to underline that the source not only claims to be noisy but appears to be so too. There's just not enough clean data here for any conclusion (wrt to a declining efficacy vs. severe disease).
- #42 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8389393/ - this paper seems to have solid data, but it simply doesn't include data on when people were vaccinated, and it uses definitions like this: "Hospitalizations among persons with breakthrough infection were defined as new hospital admissions among persons fully vaccinated on the reporting day." - in other words, a mixture of people that are vaccine-protected, and those that have had the jab but not the time to become protected. And the paper does not track how long ago people were vaccinated - so how does the lancet article then try to split this into early vs. late groups? Presumably by calendar date, which I don't think is reasonable; at least not reasonable enough.
- #43 https://www.medrxiv.org/content/10.1101/2021.08.24.21262423v... - and I'm just going to believe they copied the results correctly, but notably that paper concludes: "The efficacy of the vaccine against severe disease for the 60+ age group also decreases; from 91% to 86% between those vaccinated four months to those vaccinated six months before the study. The corresponding efficacies for the 40-59 age group are 98% and 94%. Thus, the vaccine seems to be highly effective even after six months compared to the unvaccinated population, but its effectiveness is significantly lower than it was closer to the vaccination date."
So when they say this: "Given the data gaps, any wide deployment of boosters should be accompanied by a plan to gather reliable data about how well they are working and how safe they are. Their effectiveness and safety could, in some populations, be assessed most reliably during deployment via extremely large-scale randomisation,17 preferably of individuals rather than of groups." - that makes sense; I can understand that.
But this on the other hand: "To date, none of these studies has provided credible evidence of substantially declining protection against severe disease, even when there appear to be declines over time in vaccine efficacy against symptomatic disease." - seems to be contradicted by their own sources.
Given the data they themselves cite and in addition the many more sources demonstrating that protection from infection wanes (not just antibody levels), it seems implausible to assume that protection from severe disease won't wane significantly as well, even if they're right in saying we don't know for certain or by how much.
However, even the waning already demonstrated in the #43 data set represents approximately a 50% increase in the number of hospitalizations and an increase in transmissibility after less than 8 months. Saying it's "still very high" is surely true, but the way they paint boosters as somehow plausibly unnecessary smells like motivated reasoning to me.
They clearly make the case for greater third world vaccination; as an ethical argument that makes sense. But the claim that boosters likely won't be useful strikes me as being a little creative with their sources.
Furthermore, while the article goes to great lengths to question the utility of booster shots, it does not similarly make the case that avoiding booster shots will actually materially increase vaccinations elsewhere. And while that seems plausible at first glance, there are also reasons to think that's not really true: e.g. are the boosters going to be diverted from production or will they simply be usage of already distributed shots that weren't taken up by the vaccine hesitant (which could be logistically impossible to redistribute in time)? How many people will be both eligible and willing to take a booster, and how does that compare to the number of exported doses - it might not amount to much? Is the timing of the boosters early enough that there will still be a significant export crunch? Is there really a tradeoff here at all, or will by the time boosters are used in significant numbers (say 100 million) other production be ample too?
I don't think the article really makes a very thoughtful case, at all. It doesn't really support the notion that boosters will impact supply elsewhere by the time they're deployed, and it's claiming evidence supporting booster utility is slim, but it's not quite as slim as they make out, and again - by the time boosters are widely used, if the evidence we do have so far continues to build in that vein - there will be ample evidence then.
Sure, there is a plausible future in which boosters have unexpectedly low utility, yet high uptake, and are mostly doses from new production as opposed to older, already locally distributed doses, all while third-world vaccination remains highly supply constrained. That's a future to avoid. But the paper doesn't make the case it's a likely future, nor even that it'd be hard to see it coming and thus needs action today.