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Comment by spfzero | Hacker News Reader

I think partly what's going on is that some people have immune systems that have a hard time generating an effective response, whether or not they area vaccinated. Vaccination gives the immune system a chance to respond and memorize, as best it can. If it can't do that effectively, there is higher likelihood of a serious outcome.

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I think this is very unlikely to significantly explain what we’ve seen. It’s much more likely just the natural result of artificial immunity waning much more rapidly than naturally acquired. As well as the fact that natural immunity involves exposure to the whole virus and therefore much broader types of epitopes for the immune system to “learn”.

In addition, intramuscular vaccines only provide blood/serum antibodies, while nasal infection also provides nasal/mucosal antibodies. Those who recover from Covid infection gain sterilizing immunity (less than 1% will be reinfected) that stops future infections in the upper respiratory tract.

That's why the CDC website says Covid (leaky, non-sterilizing) vaccines only provide protection (in blood) against serious illness, not infection (in nose). A future nasal vaccine may provide sterilizing immunity (what most people assume they are getting from a "vaccine", like their personal experience with the MMR vaccine).

I think these things are hard to be sure about, but there still is good evidence that covid vaccines are sterilizing in a lot of cases. The rate of infection is still lower for vaccinated people right when controlling for other demographics?

>there still is good evidence that covid vaccines are sterilizing in a lot of cases.

What? No, there isn't. The Covid vaccines we have today are not sterilizing. Period. This isn't a conspiracy theory or anything like that, it's just a simple fact.

Maybe I'm just not understanding the terms correctly. My understanding is that covid vaccines do still reduce the odds of becoming infected with covid when exposed. We don't have conclusive evidence of this because the sort of people who get vaccinated aren't identical to those who don't but it's decently convincing just based on case counts. I also see a number of studies suggesting vaccination reduces the probability of spreading covid even with delta.

Covid vaccines reduce symptoms. They increase the risk of asymptomatic transmission, since the person would otherwise self-isolate.

BBC article on immunity, https://www.bbc.com/news/health-58270098

> There is a whole different suite of antibodies (known as immunoglobulin As) in the nose and lungs, compared with those (immunoglobulin Gs) that we measure in the blood. The former is more important as a barrier to infection. Natural infection, because it is in the nose rather than a jab in the arm, may be a better route to those antibodies, and nasal vaccines are being investigated too.

Intramuscular (arm injection) vs intranasal (inhaled) vaccines: https://news.ycombinator.com/item?id=28165287

Nasal vaccine trials: https://news.ycombinator.com/item?id=28284504

>They increase the risk of asymptomatic transmission, since the person would otherwise self-isolate.

This is conjecture. It's a hypothetical effect to take into consideration, but it's certainly not borne out in data that the vaccines increase asymptomatic transmission, much less for this reason.

Let's look at the CDC website, https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vac...

> Based on evolving evidence, CDC recommends fully vaccinated people get tested 5-7 days after close contact with a person with suspected or confirmed COVID-19.

For many people, this description could apply to daily activity, e.g. riding on public transit. So the CDC is recommended regular testing of vaccinated people. Since the vaccine can suppress symptoms, testing can be used to detect infection earlier, enabling isolation and/or treatments which only work early in the progression of Covid.

In a July 2021 paper from academics advising UK SAGE, https://www.gov.uk/government/publications/long-term-evoluti...

> Whilst we feel that current vaccines are excellent for reducing the risk of hospital admission and disease, we propose that research be focused on vaccines that also induce high and durable levels of mucosal immunity in order to reduce infection of and transmission from vaccinated individuals. This could also reduce the possibility of variant selection in vaccinated individuals.

Note the reference to transmission from vaccinated individuals. There was also a study of Vietnamese healthcare workers, showing that 70% of infections were pre-symptomatic, https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3897733

> 69 healthcare workers were tested positive for SARS-CoV-2. 62 participated in the clinical study. 49 were (pre)symptomatic ... Breakthrough Delta variant infections are associated with high viral loads, prolonged PCR positivity, and low levels of vaccine-induced neutralizing antibodies, explaining the transmission between the vaccinated people. Physical distancing measures remain critical to reduce SARS-CoV-2 Delta variant transmission.

None of this indicates the vaccines increase asymptomatic transmission. Yes, breakthrough cases can still transmit. Keyword can.

70% pre-symptomatic transmission in healthcare workers with PPE is a bit more than can.

A sterilizing vaccine means that you cannot get infected when the vaccine works successfully. Not "less likely to get infected" or "less likely to experience severe symptoms if you get infected" like the Covid vaccines.

COVID-19 vaccines aren't sterilizing to any meaningful extent. They provide only limited and temporary protection against infection. The real benefit is in protection against severe symptoms.

https://www.nature.com/articles/d41586-021-02689-y

"sterilizing" seems to get a different definition every time I hear it.

There's a stable definition in textbooks.

If 2021 consumer media is offering variable definitions, Cui Bono?

I think also something that should be considered how the vaccine works if the immune system is already battling something. Anecdotally I know a person who's tumor had doubled in size after she took the vaccine. It could be coincidence. But at the same time, do we know how much an immune system directs it resources, and does it prioritize and immediate infection vs one that is latent.

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