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Comment by space_fountain | Hacker News Reader

Edit: My understanding of the science here was at least slightly wrong. Please see the reply from LurkingPenguin and eventually my reply to them

I think results like vaccinated individuals “can” have viral loads as high as unvaccinated individuals are next to useless. I need to know how likely I am to have high viral loads and my understanding of the science there is that vaccines still do a decent job of lowering the odds. I know you aren’t really arguing against vaccination here, but it seems like it needed to be said and I think the “vaccinated individuals can have high viral loads” line is particularly bad

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> I think the “vaccinated individuals can have high viral loads” line is particularly bad

https://www.medrxiv.org/content/10.1101/2021.09.28.21264262v...

https://www.ucdavis.edu/health/covid-19/news/viral-loads-sim...

How is a statement about what some researchers are finding "particularly bad"? If vaccinated individuals routinely have viral loads as high as those seen in unvaccinated individuals, it warrants more research into how the virus affects their bodies and what, if any, risks they might face both short term and long term.

According to one study[1], vaccination reduces the risk of long COVID by 49%. Given that some studies have found the incidence of long COVID is in the double digit percentages[2], exploring this issue is not purely academic. It is pertinent to the hundreds of millions of vaccinated individuals who are still at risk of infection, even if their risk of hospitalization and death has been significantly reduced.

Science works when we ask and investigate important questions. It doesn't work when we ignore these questions because we're afraid of the optics and how they might be misconstrued by some people.

In fact, when it comes to COVID generally, it seems evident to me that shying away from difficult questions has had the opposite of the intended effect. It has probably caused more people to adopt anti-science views and reject beneficial measures like vaccination.

[1] https://www.usnews.com/news/health-news/articles/2021-09-02/...

[2] https://www.medicalnewstoday.com/articles/more-than-one-thir...

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.

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.

Welp, this is making me realize I was just wrong. My understanding of the science was something like you can find asymptomatic vaccinated individuals with similar viral loads to asymptomatic unvaccinated people, which is a bit meaningless when you're choosing a threshold for "infected" and when random chance will just see some people at any level. So to be clear it's not that I think the questions shouldn't be investigated, but a statement like "some vaccinated cases have high viral loads" is meaningless to explaining what my risk of spreading covid is.

Trying to avoid the sort of bias that comes from trying to reinforce rather than question existing views, but I do still think the statement "No Significant Difference in Viral Load Between Vaccinated and Unvaccinated, Asymptomatic and Symptomatic Groups Infected with SARS-CoV-2 Delta Variant" despite being much more precise is still a bit unintuitive in it's implication. Because essentially what this means right is that they sampled people's viral loads, and then cut out everyone below a value they choose to mean "infected". It's still true that even if I had symptoms because I'm vaccinated my odds of having a high viral load are much lower. Presumably if you didn't remove all the samples with less than some concentration you'd see significant differences.

I think that something the scientists got wrong consistently with covid was not unflinchingly communicating what was likely to be true mostly out of a fear that the public would take interventions that only moderately improved their safety like wearing a mask, and start doing riskier things or because of a bias towards doing nothing when clear evidence didn't exist. It can feel like similar things are happening with vaccination where it does seem pretty clear that getting vaccinated reduces your risk of passing on covid both because you're less likely to ever get a colony of the virus sufficient to count as "infected" and because you're likely to have a shorter infection.

> Because essentially what this means right is that they sampled people's viral loads, and then cut out everyone below a value they choose to mean "infected".

Huh? Please cite the part of the study you're referring to to argue that the title of the study means the exact opposite of what it says.

Every manufacturer of a PCR test specifies a Ct cutoff above which the result is considered false.

> It's still true that even if I had symptoms because I'm vaccinated my odds of having a high viral load are much lower. Presumably if you didn't remove all the samples with less than some concentration you'd see significant differences.

The study says the exact opposite:

> There were no statistically significant differences in mean Ct-values of vaccinated (UeS: 23.1; HYT: 25.5) vs. unvaccinated (UeS: 23.4; HYT: 25.4) samples. In both vaccinated and unvaccinated, there was great variation among individuals, with Ct-values of <15 to >30 in both UeS and HYT data (Fig. 1A, 1B). Similarly, no statistically significant differences were found in the mean Ct-values of asymptomatic (UeS: 24.3; HYT: 25.4) vs. symptomatic (UeS: 22.7) samples, overall or stratified by vaccine status (Fig. 1B). Similar Ct-values were also found among different age groups, between genders, and vaccine types (Supplemental Figure 1).

> The study says the exact opposite:

Maybe I'm misinterpreting the study. I interpreted that as being among the fraction of people who are infected both because that's what the title says, and because they say later that "75% of the positive samples were from unvaccinated individuals" which would seem to be inconsistent with the groups having similar viral loads.

I thought we were dealing with a random variable composed something like this

VIRAL_LOAD = INFECTED ? LOAD_FOR_INFECTED : LOAD_FOR_UNINFECTED

And the study is saying that the random variable `LOAD_FOR_INFECTED` isn't correlated with vaccination status. That's indeed an interesting fact, but since `INFECTED` still was correlated (I think) overall for some random person `VIRAL_LOAD` would be too. Honestly a table would make all of this more clear.

> Maybe I'm misinterpreting the study.

With no offense intended, I think you're misunderstanding the whole concept of "viral load". If you are not infected with SARS-CoV-2, you don't have a SARS-CoV-2 "viral load".

I was sort of intentionally abusing the term, though I was trying to be clear that I was trying include explicitly people with a number of viral particles low enough to not be infected. My understanding is that a single covid virus infecting a cell won't result in a positive covid test and probably won't make someone sick especially if they're vaccinated. More broadly the point I'm trying to make is that vaccination lowers the expected value of covid shedding because even if they're actually infected they might spread just as well they're less likely to be infected and that phrases like vaccinated people have similar viral loads to unvaccinated individual obscures that point and helps lead people to think vaccines are useless

> phrases like vaccinated people have similar viral loads to unvaccinated individual obscures that point and helps lead people to think vaccines are useless

I neither stated nor implied any such thing and these sorts of PSAs are really not constructive. HN I believe has a generally well-educated and technical audience that is capable of having intelligent, nuanced conversation about scientific research.

In fact, with all due respect, given that you've repeatedly misconstrued and misunderstood the research presented, and by your own admission abused terms, all in an effort to argue something that was totally unrelated to what was being discussed, I'd suggest your efforts are actually counterproductive.

Maybe I should have been more concrete earlier. I certainly didn't mean to obscure my meaning or make you feel attacked. I did start out in my first reply with a mistaken understanding of the science. I did edit my post to reflect that because I didn't want to lead people astray and maybe I should have even more forcefully. But, I do think while knowing the nuance is important, It is easy to lose track of just now effective vaccines seem to be. They do for example dramatically reduce the odds that I'm currently shedding virus which is most of what I worry about. And statements like viral load being the same really do seem confusing. I also think even on here the terms are confusing. Viral load for example is only for people who are infected, but what exactly does it mean to even be infected. Certainly just having a virus land in say your nose isn't enough. I think most people wouldn't even count a few cells being infected as truly infected. Certainly a test wouldn't right? So I think talking about viral load as a quantity for people who aren't "infected" is sort of reasonable especially when "infected" is being defined essentially in terms of virus concentration. But idk much, my only bio credential is 1 year of undergraduate course work

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