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> Anticipating all the downvotes Please don't do this: "Please don't comment about the voting on comments. It never does any good, and it makes boring reading"

> Anticipating all the downvotes Please don't do this: "Please don't comment about the voting on comments. It never does any good, and it makes boring reading" [1]. > flu vaccines are extremely ineffective They're not. They're not particularly effective for preventing flu in an individual. But at the group level, they have a clear and useful effect. [1] https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html

erelong 4mo ago
Willing to discuss it but I am definitely one who thinks it's a "scam", "mainstream" example articles on ineffectiveness: "Flu vaccines didn't work that well in the US, officials find (2026)" https://abc7chicago.com/post/flu-vaccines-didnt-work-us-officials-find/18714030/ https://abc7chicago.com/post/flu-vaccines-didnt-work-us-offi... https://apnews.com/article/flu-season-cdc-subclade-k-vaccination-11952f89201d2396ec0c52461441c82b https://apnews.com/article/flu-season-cdc-subclade-k-vaccina... "Flu Vaccine Was Not Very Effective This Season, the C.D.C. Says (2022)" https://www.ncbi.nlm.nih.gov/search/research-news/15706/ https://www.ncbi.nlm.nih.gov/search/research-news/15706/ "Flu shot fail: Why doesn't the vaccine always work? (2014)" https://www.nbcnews.com/health/health-news/flu-shot-fail-why-doesn-t-vaccine-always-work-n21446 https://www.nbcnews.com/health/health-news/flu-shot-fail-why...
- defrost 4mo ago
  The first example cites "the worst performance ever". Taking that as a given how bad was it? This season's vaccines were around 25% to 30% effective in preventing adults from getting sick enough from the flu that they had to go to a doctor's office, clinic or hospital, according to a CDC report this week. Of a hundred adults that would have had to seek medical treatment / take a day off (had there been no vaccine) 70 adults went to the doctors and 30 did not. Children who were vaccinated were about 40% less likely to get treatment at a doctor's office or hospital. (As above, of one hundred kids that would have gotten sick, 40 did not ) The questions really should be .. did people die that could have been saved, was it cost effective to vaccinate a hundred million people to reduce the percentage of those who contacted flu and then got sick (and did the vaccination reduce the numbers of people in contact). As it stands, by your examples, the flu vaccine didn't perform well that year, in comparison to others, but it hardly looks as though it had no effect whatsoever.
- jghn 4mo ago
  There are a handful of factors, I'll approach this as if you're acting in good faith. 1) Most people who claim to have "the flu" don't actually have influenza. Thus, if they take a flu vaccine, and get "the flu", they blame the flu 2) The vaccine does not create a perfect boundary. It's a population scale benefit. It makes it less likely one gets infected, it makes it less likely that someone who gets infected has serious disease, and it makes it less likely that someone infected passes it along 3) The "flu vaccine" is a prediction, trying to guess the strains that will be prevalent in the upcoming season Sometimes they guess wrong, and it's less effective. If we supported mRNA technology this could be improved.
- jlebar 4mo ago
  It's an amazing fact of mathematics that even a vaccine that has relatively low efficacy can completely neutralize transmission if enough people in a group take it. This is especially true in the case of the flu because it has a relatively low R0 of approximately 1.3, meaning that without intervention/vaccines, each infected individual infects on average 1.3 other people. The vaccine just needs to be effective enough to drive the reproduction rate below 1 for the virus to die out. We do not have good data on how effective flu vaccines are at neutralizing transmission. But for the sake of argument, let's take these relatively "bad" years for the flu where they prevented 40% of doctor's visits. Suppose that corresponds to merely preventing 40% of transmissions. The other 60% of transmissions still occur. In that case is it even possible to drive R_eff (the effective reproduction rate of the virus) below 1? It turns out, yes! With an R0 of 1.3 and an effectiveness of only 40%, you stop the spread of the virus after vaccinating only 60% of people. Details on the math: https://claude.ai/share/8e8ffef7-ba33-44aa-a2a6-ca3b9be6d516 https://claude.ai/share/8e8ffef7-ba33-44aa-a2a6-ca3b9be6d516. You can also extend the conversation and ask more questions!
ifyoubuildit 4mo ago
> They're not. They're not particularly effective for preventing flu in an individual. But at the group level, they have a clear and useful effect. This is my understanding. It basically would have marginally reduced the cost of the flu coming through, right? But thats not the impression that I would get from any of the discussion here. Am I wrong?
- jlebar 4mo ago
  Parent poster is saying that even though the effect on an individual is low relative to other vaccines, the effect of a whole group taking the vaccine is actually very high. This the opposite of your understanding. The benefit to the individuals in a group from the whole group taking the vaccine is actually much larger than the benefit to an individual in the group of taking the vaccine solo. You can read more about it here (and ask more questions!). https://claude.ai/share/8e8ffef7-ba33-44aa-a2a6-ca3b9be6d516 https://claude.ai/share/8e8ffef7-ba33-44aa-a2a6-ca3b9be6d516
  - ifyoubuildit 4mo ago
    Are you sure? Your link ends with this: > Combined with the brutal arithmetic at higher R0R_0 R0 , this is a large part of why flu vaccination programs are generally justified on individual protection against illness and severe outcomes rather than on a realistic expectation of achieving herd immunity and stopping circulation. On the one hand, in a military setting you can feasibly achieve 100% compliance. But if you don't stop transmission (which it sounds like we don't have good data saying it would), you don't get herd immunity. So I think you're back to just the benefits of reduction in disease, which is not nothing, but it is marginal like I said originally.
    - jlebar 4mo ago
      I mean, I would say that preventing 40% of disease (depending on what you're measuring, etc etc) is not marginal. I guess I'd turn it around and ask, if 40% is marginal, what number would not be marginal, and why do you draw the line there? (For me, "marginal" would mean that the costs were roughly equal to the benefits. I think you'd have a hard time convincing me that saving the lives of even just 1% of the people who would normally die from the flu -- between 10k and 50k people a year -- is roughly equivalent to the cost of giving out flu shots. I suppose you could argue that the benefit is marginal to individuals who have a low probability of dying from the flu, and marginal to a society which has relatively low vaccination rates overall.) The other thing is that, according to the Claude data here, the vaccine is actually relatively effective at preventing the transmission of some flu variants, 50% effective against influenza B! If so, there would be a clear group benefit to that, you only need (1 - 1/1.3) / 0.5 = 46% of people to be vaccinated to achieve herd immunity to that strain.

erelong 4mo ago

Willing to discuss it but I am definitely one who thinks it's a "scam", "mainstream" example articles on ineffectiveness: "Flu vaccines didn't work that well in the US, officials find (2026)" https://abc7chicago.com/post/flu-vaccines-didnt-work-us-officials-find/18714030/ https://abc7chicago.com/post/flu-vaccines-didnt-work-us-offi... https://apnews.com/article/flu-season-cdc-subclade-k-vaccination-11952f89201d2396ec0c52461441c82b https://apnews.com/article/flu-season-cdc-subclade-k-vaccina... "Flu Vaccine Was Not Very Effective This Season, the C.D.C. Says (2022)" https://www.ncbi.nlm.nih.gov/search/research-news/15706/ https://www.ncbi.nlm.nih.gov/search/research-news/15706/ "Flu shot fail: Why doesn't the vaccine always work? (2014)" https://www.nbcnews.com/health/health-news/flu-shot-fail-why-doesn-t-vaccine-always-work-n21446 https://www.nbcnews.com/health/health-news/flu-shot-fail-why...

defrost 4mo ago
The first example cites "the worst performance ever". Taking that as a given how bad was it? This season's vaccines were around 25% to 30% effective in preventing adults from getting sick enough from the flu that they had to go to a doctor's office, clinic or hospital, according to a CDC report this week. Of a hundred adults that would have had to seek medical treatment / take a day off (had there been no vaccine) 70 adults went to the doctors and 30 did not. Children who were vaccinated were about 40% less likely to get treatment at a doctor's office or hospital. (As above, of one hundred kids that would have gotten sick, 40 did not ) The questions really should be .. did people die that could have been saved, was it cost effective to vaccinate a hundred million people to reduce the percentage of those who contacted flu and then got sick (and did the vaccination reduce the numbers of people in contact). As it stands, by your examples, the flu vaccine didn't perform well that year, in comparison to others, but it hardly looks as though it had no effect whatsoever.
jghn 4mo ago
There are a handful of factors, I'll approach this as if you're acting in good faith. 1) Most people who claim to have "the flu" don't actually have influenza. Thus, if they take a flu vaccine, and get "the flu", they blame the flu 2) The vaccine does not create a perfect boundary. It's a population scale benefit. It makes it less likely one gets infected, it makes it less likely that someone who gets infected has serious disease, and it makes it less likely that someone infected passes it along 3) The "flu vaccine" is a prediction, trying to guess the strains that will be prevalent in the upcoming season Sometimes they guess wrong, and it's less effective. If we supported mRNA technology this could be improved.
jlebar 4mo ago
It's an amazing fact of mathematics that even a vaccine that has relatively low efficacy can completely neutralize transmission if enough people in a group take it. This is especially true in the case of the flu because it has a relatively low R0 of approximately 1.3, meaning that without intervention/vaccines, each infected individual infects on average 1.3 other people. The vaccine just needs to be effective enough to drive the reproduction rate below 1 for the virus to die out. We do not have good data on how effective flu vaccines are at neutralizing transmission. But for the sake of argument, let's take these relatively "bad" years for the flu where they prevented 40% of doctor's visits. Suppose that corresponds to merely preventing 40% of transmissions. The other 60% of transmissions still occur. In that case is it even possible to drive R_eff (the effective reproduction rate of the virus) below 1? It turns out, yes! With an R0 of 1.3 and an effectiveness of only 40%, you stop the spread of the virus after vaccinating only 60% of people. Details on the math: https://claude.ai/share/8e8ffef7-ba33-44aa-a2a6-ca3b9be6d516 https://claude.ai/share/8e8ffef7-ba33-44aa-a2a6-ca3b9be6d516. You can also extend the conversation and ask more questions!

ifyoubuildit 4mo ago

> They're not. They're not particularly effective for preventing flu in an individual. But at the group level, they have a clear and useful effect. This is my understanding. It basically would have marginally reduced the cost of the flu coming through, right? But thats not the impression that I would get from any of the discussion here. Am I wrong?

jlebar 4mo ago
Parent poster is saying that even though the effect on an individual is low relative to other vaccines, the effect of a whole group taking the vaccine is actually very high. This the opposite of your understanding. The benefit to the individuals in a group from the whole group taking the vaccine is actually much larger than the benefit to an individual in the group of taking the vaccine solo. You can read more about it here (and ask more questions!). https://claude.ai/share/8e8ffef7-ba33-44aa-a2a6-ca3b9be6d516 https://claude.ai/share/8e8ffef7-ba33-44aa-a2a6-ca3b9be6d516
- ifyoubuildit 4mo ago
  Are you sure? Your link ends with this: > Combined with the brutal arithmetic at higher R0R_0 R0 , this is a large part of why flu vaccination programs are generally justified on individual protection against illness and severe outcomes rather than on a realistic expectation of achieving herd immunity and stopping circulation. On the one hand, in a military setting you can feasibly achieve 100% compliance. But if you don't stop transmission (which it sounds like we don't have good data saying it would), you don't get herd immunity. So I think you're back to just the benefits of reduction in disease, which is not nothing, but it is marginal like I said originally.
  - jlebar 4mo ago
    I mean, I would say that preventing 40% of disease (depending on what you're measuring, etc etc) is not marginal. I guess I'd turn it around and ask, if 40% is marginal, what number would not be marginal, and why do you draw the line there? (For me, "marginal" would mean that the costs were roughly equal to the benefits. I think you'd have a hard time convincing me that saving the lives of even just 1% of the people who would normally die from the flu -- between 10k and 50k people a year -- is roughly equivalent to the cost of giving out flu shots. I suppose you could argue that the benefit is marginal to individuals who have a low probability of dying from the flu, and marginal to a society which has relatively low vaccination rates overall.) The other thing is that, according to the Claude data here, the vaccine is actually relatively effective at preventing the transmission of some flu variants, 50% effective against influenza B! If so, there would be a clear group benefit to that, you only need (1 - 1/1.3) / 0.5 = 46% of people to be vaccinated to achieve herd immunity to that strain.