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Doesn't that just raise the question of why an at-risk elderly person wouldn't get the flu shot to protect themselves from all the people who don't? I've heard

by Jach 9y ago

Doesn't that just raise the question of why an at-risk elderly person wouldn't get the flu shot to protect themselves from all the people who don't? I've heard this irresponsibility argument a lot, I understand it, but I think it's overblown. Herd immunity works best when the vaccine is actually effective. For flu vaccines, every year they're not very effective.

lutorm 9y ago
Even if they do, since the vaccine is not 100% effective it still helps if other people are vaccinated since it decreases the chance of them getting it in the first place.
opportune 9y ago
The vaccine is still >30% effective. And you may be confused regarding how vaccines for things like the flu work: they have varying efficacy against different strains but getting vaccinated for a certain strain does not at all mean you won't get sick with that strain - it reduces the likelihood. Imagine all the people in the world as a graph with weighted edges representing the probability of one person transmitting the flu to another. The more people become vaccinated, the less the weights of the edges, and the less people get sick overall.
- Jach 9y ago
  Sure, I'm not disputing that flu vaccines suck compared to vaccines for other things. I'm just disputing that "irresponsibility" is a poor argument against those who decide not to get one, given that the flu vaccines suck, and given the greatest magnitude intervention for an at-risk person ought to be getting the vaccine themselves no? (If you wanted to make a stronger argument for irresponsibility, I think you'd need to provide some actual numbers. Raising or lowering the likelihood doesn't mean much without knowing the magnitude and what the base rates are. After that one could attempt to translate it into a measure of irresponsibility, but that's probably where most of the less productive arguments would happen, including what-about comparisons to other choices that may or may not have much greater impact magnitude like not coming to work while feeling sick, so there's still not much point to the exercise.)
  - lutorm 9y ago
    Think of it this way: If the vaccine is, say, 30% effective, then a single person vaccinating themselves will bring their risk down by 30%. But if there are N people between that person and patient zero, and all those people are vaccinated, the risk is brought down by 1-0.7^N. For the virus to propagate through a chain of 3 vaccinated people that comes out to 66%, an effect more than twice as effective as that of just the person getting the vaccine themselves. (It's more complicated than that, especially since getting the flu isn't binary, but it should give an indication of how the effects scale.)
    - julianj 9y ago
      > For the virus to propagate through a chain of 3 vaccinated people that comes out to 66%, an effect more than twice as effective as that of just the person getting the vaccine themselves. Is this true if the vaccine is ineffective against the strain which is circulating or is the effectiveness of the vaccine partly chance? Genuinely curious.

by Jach 9y ago

lutorm 9y ago

Even if they do, since the vaccine is not 100% effective it still helps if other people are vaccinated since it decreases the chance of them getting it in the first place.

opportune 9y ago

The vaccine is still >30% effective. And you may be confused regarding how vaccines for things like the flu work: they have varying efficacy against different strains but getting vaccinated for a certain strain does not at all mean you won't get sick with that strain - it reduces the likelihood. Imagine all the people in the world as a graph with weighted edges representing the probability of one person transmitting the flu to another. The more people become vaccinated, the less the weights of the edges, and the less people get sick overall.

Jach 9y ago
Sure, I'm not disputing that flu vaccines suck compared to vaccines for other things. I'm just disputing that "irresponsibility" is a poor argument against those who decide not to get one, given that the flu vaccines suck, and given the greatest magnitude intervention for an at-risk person ought to be getting the vaccine themselves no? (If you wanted to make a stronger argument for irresponsibility, I think you'd need to provide some actual numbers. Raising or lowering the likelihood doesn't mean much without knowing the magnitude and what the base rates are. After that one could attempt to translate it into a measure of irresponsibility, but that's probably where most of the less productive arguments would happen, including what-about comparisons to other choices that may or may not have much greater impact magnitude like not coming to work while feeling sick, so there's still not much point to the exercise.)
- lutorm 9y ago
  Think of it this way: If the vaccine is, say, 30% effective, then a single person vaccinating themselves will bring their risk down by 30%. But if there are N people between that person and patient zero, and all those people are vaccinated, the risk is brought down by 1-0.7^N. For the virus to propagate through a chain of 3 vaccinated people that comes out to 66%, an effect more than twice as effective as that of just the person getting the vaccine themselves. (It's more complicated than that, especially since getting the flu isn't binary, but it should give an indication of how the effects scale.)
  - julianj 9y ago
    > For the virus to propagate through a chain of 3 vaccinated people that comes out to 66%, an effect more than twice as effective as that of just the person getting the vaccine themselves. Is this true if the vaccine is ineffective against the strain which is circulating or is the effectiveness of the vaccine partly chance? Genuinely curious.