[ifyoubuildit]

> herd immunity absolutely exists

Yes. Who said otherwise?

> and is an effective way of reducing the spread of viruses at scale, sometimes significantly so.

I don't follow. Doesn't herd immunity mean the herd is immune? As in, there is no transmission and the pathogen either dies or fades to the background?

Either way, eventually almost everyone caught covid (obviously with some exceptions), no matter how many shots you got or didn't get.

The strongest point in favor of the "social good" argument is that the shots reduced severity of infection, thereby reducing hospitalizations and freeing up hospital beds for random accidents. But the overflowing hospitals issue wasnt nearly as bad as it was made out to be as I understand it. And we'll probably never know for sure how many hospitalizations were caused by the shots themselves, because only lunatics think that something with vaccine in the name can harm you.

[verandaguy]

> I don't follow. Doesn't herd immunity mean the herd is immune? As in, there is no transmission and the pathogen either dies or fades to the background?

In a perfect world where everyone gets vaccinated and vaccines are 100% effective in all people against all individuals of a strain, yeah, probably. In reality, not everyone gets vaccinated, and not everyone reacts well to the vaccine, and sometimes individuals from a strain slip by, so no. Some individuals from a strain will survive, some people will catch it and get sick, and of those surviving the sickness, they'll become the breeding ground for a new mutation.

> Either way, eventually almost everyone caught covid (obviously with some exceptions), no matter how many shots you got or didn't get.

Source? The latest data shows that out of ~40 million Canadians, about 4.8 million or about 12% are reported to have tested positive for Covid at any point and been recorded as such. Globally, the figure is about 775 million out of 8 billion[0].

Among vaccinated Canadians, CCDR 2024 Vol. 50 published by the PHAC[1] shows that both despite waning immunity from the vaccines (which is partially attributable to the poor understanding of what would both be safe for humans and long-term effective against Covid) as well as the emergence of new variants both causing spikes in overall case count and associated stats (like hospital admissions and deaths), vaccinated people were measurably less likely to contract the disease and to fall severely ill if they did. This is roughly in line with your comment about vaccines reducing infection severity.

The study is a relatively quick read and I encourage you to give it a look if you have the stomach for medical statistics (which admittedly is pretty dry). The methodology is nothing special, but not problematic IMO, and the sample size and population distribution are good for a study of this scale (though there's an overrepresentation of the unvaccinated relative to the Canadian population; in this case, it likely doesn't represent an issue).

    [0] https://data.who.int/dashboards/covid19/cases?n=c
    [1] https://www.canada.ca/en/public-health/services/reports-publications/canada-communicable-disease-report-ccdr/monthly-issue/2024-50/issue-1-2-january-february-2024/covid-19-outcome-trends-vaccination-status-canada.html

[ifyoubuildit]

Here's a source for the US in Q3 2022:

> By the third quarter of 2022, an estimated 96.4% of persons aged ≥16 years in a longitudinal blood donor cohort had SARS-CoV-2 antibodies from previous infection or vaccination, including 22.6% from infection alone and 26.1% from vaccination alone; 47.7% had hybrid immunity.

Doing the math, that estimates ~70% of US blood donors over 16 had contracted actual covid by almost 2 years ago.

(https://www.cdc.gov/mmwr/volumes/72/wr/mm7222a3.htm)

Are blood donors representative? I don't know. Reported and recorded positives doesn't seem at all representative of an overall infection count though, since it misses probably most minor cases of covid, which makes up most cases period.

[verandaguy]

I can't really say whether or not blood donors are representative (most likely that has little impact on the results of the study), but the sample size is much smaller: an initial cohort of 142,758 from July 2021 was reduced down to a final sample size of N=72,748 because of the availability of robust records of immunization and disease history in the context of the study. This represents roughly 0.02%, which may be representative if the sampling was done well, (it likely was, the CDC tends to do good work in that regard), but isn't as robust as the study by the PHAC.

This final cohort was studied based on records generated and collected in four three-month periods between April 2021 and September 2022 which is a good timeline.

This study seems to focus on the efficacy of older (≥65 years) people sticking to a strict vaccination schedule, which is reflected in the numbers; in that age group, vaccination-linked immunity is highest. The counterpoint to that is that younger groups aren't sticking to as strict a vaccination schedule, though best as I can tell, the study stops short of spelling that out, so that's my own conclusion.