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Comment by walterbell | Hacker News Reader

Recent Mayo Clinic study estimated Pfizer was 42% effective against Delta, https://www.medrxiv.org/content/10.1101/2021.08.06.21261707v...

> However, in July, the effectiveness against infection was considerably lower for [Moderna] mRNA-1273 (76%, 95% CI: 58-87%) with an even more pronounced reduction in effectiveness for [Pfizer] BNT162b2 (42%, 95% CI: 13-62%). Notably, the Delta variant prevalence in Minnesota increased from 0.7% in May to over 70% in July whereas the Alpha variant prevalence decreased from 85% to 13% over the same time period.

> there's little evidence that patients (vaccinated or unvaccinated) have worse outcomes with delta; they're just more likely to spread it

Entirely possible, as viruses historically evolve to be weaker and more transmissible. That would be good news.

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Many other studies disagree with that one. Current consensus is that the Pfizer vaccine is well over 90% effective against severe disease from Delta, and over 80% for infection:

https://nitter.net/mugecevik/status/1430218372348878860?lang...

We also have the study reported in this article.

> Nursing home residents, health care workers lose more than 80% of their COVID-19 immunity six months after Pfizer vaccine.

That sentence is extremely misleading. The study showed people losing more than 80% of their antibody immunity. But they also have T-cell and B-cell immunity which lasts longer.

Here's a third study, from Qatar, based on positive PCR tests in recipients of Pfizer vaccines, which estimated 0% (not a typo) vaccine effectiveness against symptomatic infection after 20 weeks, https://news.ycombinator.com/item?id=28548322

It seems like a broken record but you don't need active antibodies to have protection from the vaccine. Antibodies give you protection in that moment. If you have no antibodies, you are extremely likely to test positive because the virus -- temporarily -- can freely enter your cells and replicate. However, other immune system components quickly identify the invader, re-boost antibodies, and crush the infection.

Expecting the vaccine to produce high antibody counts for life is not how our immune systems work.

>...estimated 0% (not a typo) vaccine effectiveness against symptomatic infection after 20 weeks

That's also extremely misleading. The greatest vaccine benefit is not elimination of merely symptomatic infection, but to reduce serious symptoms (i.e. hospitalization) and death.

Here's what the study says about that:

Meanwhile, BNT162b2-induced protection against hospitalization and death appears to persist with hardly any waning for at least six months following the second dose.

It's good that the CDC updated their definition of vaccine to make it clear to the general population that non-sterilizing Covid vaccines provide "protection" and not "immunity", to reset the expectations of vaccine recipients who may have believed that Covid vaccination provided immunity or stopped transmission.

It’s unfortunate however that public policies in most western countries haven’t adapted to that fact yet (which has been a serious hypothesis since the beginning). they still encourage risk-free patients to get vaccinated in the hope of herd immunity. It’s just sad.

That's interesting. If that bears out, it suggests without antibody immunity people will get infected by COVID. However, that same study also shows that the vaccine still prevents serious illness and death, i.e. those other immunity mechanisms are still there and effective, just not kicking in quickly enough to block infection. So "lose more than 80% of their COVID-19 immunity" is still misleading.

> Qatar

> estimated 0% (not a typo) vaccine effectiveness

yes, that is ridiculous.

pretty certain that study is mostly fit for toilet paper.

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