Samira wrote:
1. Yes, the virus does mutate. However, we get a sneak peek a year or more in advance of any particular virus spreading throughout a given population, and that's the lead time we need to develop a vaccine for two or three of the more threatening viruses;
Sure. But it's a guessing game. If you get the right vaccine during the time period it's effective, your chance of not getting sick to that particular flu strain is significantly lower. No one's arguing this. But there's no indication that the odds of *you* getting the flu (ie: any random flu strain) this year is in any way affected by the percentage of people in the population as a whole who receive a vaccine.
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2. The flu vaccine is effective for about six months, easily covering the worst of the flu season;
I've heard three months. It's why people who work with people with compromised immune systems get them every 3 months.
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3. "Poor responders" include the chronically ill, the very young, and the very old, which is exactly why the rest of us need to be immunized to help protect them. That is how herd immunity works in the real world;
No. Poor responders are those who respond poorly to the vaccine. Specifically, those for whom the vaccine either will provide no immunity, reduced immunity, or shortened immunity. And while this can (and certainly does) intersect with the set you are speaking of, I used this term separately from that set because I was specifically referring to otherwise healthy people who simply wont gain immunity if they take a vaccine (or will still be able to transmit the virus despite taking the vaccine, which is the more relevant issue).
I'm not talking about the folks we're trying to protect with herd immunity, but the people who at any given time will be able to get and pass on the flu virus regardless of their vaccination status. And at any given time, there will always be a percentage of the population in this category for any of a number of reasons.
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4. If every person were immunized every year, flu would not be a major heath concern. See? I can cite my opinion as fact, too!
Yay!
We've seen outbreaks among populations where immunization was 98% or higher. And no, the point isn't about the percentage of those who got sick being mostly those who didn't get a vaccination. The point is that they were not actually protected by being surrounded by a herd of people who did. Ergo, herd immunity didn't work. There's just too many vectors of infection in the population for it to work, and even a small percentage of the whole being capable of passing on the virus will allow it to do so.
I'll say again: We're not using herd immunity if the only people protected are those who take the vaccination.
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5. Even where the flu vaccine does not provide full immunity, there is substantial evidence that it does help lessen the duration and severity of the flu.
Yes. But herd immunity only takes effect if they can't pass on the flu, not just by having reduced symptoms. Hence, the problem. A percentage of people will have reduced symptoms as a result of the vaccination, but still be able to pass it on. This can arguably be *worse* from a herd infection perspective because mildly sick people will tend to continue trying to work and otherwise do things that will infect others, while those who get a full bore case of the flu will tend to stay home and practice safe habits. That's the problem, specifically with the flu vaccine. For many other diseases, the concept works. For the flu? There's a pretty compelling argument that herd immunity just plain doesn't take place. At least not on a broad scale.
Edited, Oct 23rd 2014 7:21pm by gbaji