Vaccine insanity–one area where the poor may benefit (#vaxfax)

Last month, the National Committee for Quality Assurance released some interesting numbers on childhood vaccination rates.  They found that childhood vaccination rates among children with commercial insurance plans (the kind you would get from an employer or purchase yourself) fell around 4%.  Vaccination rates increased among children receiving Medicaid, the government health care plan for the poor.

Vaccine rates, from NCQA The State of Health Care Quality Report 2010

The NCQA cited vaccine myths as a possible reason.  Wealthier families—those than can afford private insurance—may have more access to information, including bad information.  I have an additional hypothesis.  I just trotted across the hall to the pediatric clinic and found out that Medicaid—at least in this state—mandates certain quality practices, including the administration and recording of vaccinations.   Most commercial plans are only beginning to implement these sorts of programs.

Whatever the cause, the trend is worrisome.    Depending on factors such as geographic location and schooling, wealthy kids may be increasingly free-loading on poorer kids, benefiting from herd immunity without participating in the (minimal) risks.  This is ethically unpleasant behavior, and is bad for public health.

61 Comments

  1. Chuck

     /  November 4, 2010

    PAL,
    You seem to have a little tunnel vision on the topic.
    If any individual becomes a vector for any contagious disease, VACCINATED or not, then this statement would ultimately be true:
    “This is ethically unpleasant behavior, and is bad for public health.”

    Vaccination is irrelevant to ethical behaviors related to public health.

    • PalMD

       /  November 4, 2010

      What?

      • Chuck

         /  November 4, 2010

        Spreading any contagious disease is unethical and bad for public health. Vaccinated and unvaccinated individuals contribute to this problem.

        • Chris

           /  November 4, 2010

          Explain clearly how vaccinated people spread disease.

          • Chuck

             /  November 4, 2010

            Simple scientific fact: Vaccines are never 100% effective. People falsely believe that they are not vectors for the contagious illness because they must just be “tired” or “coming down with a cold” and expose others unnecessarily. This is unethical behavior, vaccinated or not.

          • Chris

             /  November 4, 2010

            Okay. So it happens to less then 5% of those who have had the MMR. And more to those who had the Tdap.

            So, are you trying to argue that we not vaccinate because it is not 100% effective?

  2. What what?

  3. I’m going to go out on a limb here and pretend I understand what chuck is saying. He appears to be saying that any mode of transmitting an infectious disease is ethically equal to any other.

    If one is vaccinated but is unfortunate enough to have not become immune, you have done your “due diligence” in attempting to reduce transmission. This is very different ethically from refusing to vaccinate.

    • Chuck

       /  November 4, 2010

      You can still perform your “due diligence” without being vaccinated.

      • Kierra

         /  November 4, 2010

        Most diseases have a period in which you are contagious without feeling sick. Human nature (we like being social) means that you can’t expect to completely halt diseases by just telling people to stay home when they are sick.

        • Pertussis in particular is highly contagious and during the most contagious phase looks much like a cold.

          But Chucks doing his usual trolling. Play with him if you like, but you will soon tire.

          • Chuck

             /  November 4, 2010

            And according to CDC documentation during the 2006 Pertussis outbreak, a vast majority of the diagnosed cases were in the vaccinated population. PAL, you are always welcome to point out any falsehoods I may claim.

          • As you may or may not know, pertussis immunity wanes quickly. Revaccination is currently recommended in adults.

          • Chuck

             /  November 4, 2010

            Is there a consensus on how quickly it wanes?

          • Chris

             /  November 4, 2010

            About five to ten years. It also wanes if you get the disease and survive. Do you skip tetanus boosters because they also wane?

            Here is a little video that should help explain herd immunity:

          • Brad

             /  November 5, 2010

            So, let’s say, 95% of people are vaccinated against pertussis and 10% of those don’t develop immunity. 5% are not immunized. If everyone without immunity is exposed and gets infected, almost twice as many immunized persons will be infected than unimmunized.

            You’re looking at the wrong number.

    • Chuck

       /  November 4, 2010

      Since C. tetani is only transmitted by direct contact, the discussion of tetanus concerning herd immunity is irrelevant. Assuming that the tetanus vaccine you receive is effective, I have seen studies (I believe on Plos) that say that immunity may be longer than 10 years. That was years ago and those studies may have been discredited since then.

      That does bring up another interesting situation.

      Immunity wanes at different rates for each of the pathogens in the DTaP or Tdap vaccines. Is it recommended that you receive the Tdap booster every 10 years (CDC web site), which leaves you potentially exposed to pertussis for 5 years (per Chris). If you take the vaccine every 5 years to protect against pertussis, you are wasting resources by receiving a vaccine (tetanus) that you do not need because you are theoretically already immune.

      We all know which way the medical community will go in this situation, but it isn’t really evidenced based, is it.

      In reference to Dr. Free Ride [my changes in brackets]

      Moreover, when [anyone] make choices with the potential to impact not only themselves and their kids but also other members of the community, they have a duty to do what is necessary to minimize bad impacts on others. Among other things, this might mean keeping [any contagious individual, vaccinated or not] isolated from [everyone] because of their age, because of compromised immune function, or because they are allergic to a vaccine ingredient.

      There are no free rides, you either become a vector for contagious illness or you do not. Being vaccinated is just one degree of freedom in that calculation.

      • Chris

         /  November 5, 2010

        For a long time only vaccinating children for pertussis was effective. There was a decent amount of herd immunity. Now that does not work. So it is recommended that everyone get pertussis boosters, even those over 65.

        So when enough are vaccinated, then even those whose pertussis immunity wears off will be protected. So it is in yours and your children’s best interest to make sure everyone in the family gets either the DTaP or Tdap.

        Those who understand science understand that it is not perfect, and are willing to change to better methods. It is part of having an open mind.

        • Chuck

           /  November 5, 2010

          I don’t know how long “For a long time” is for you. You are more than welcome to go back through CDC information to see an upsurge in the number of cases of purtussis every three to four years for the past 40 years. This isn’t like the stock market, it is an easy trend to spot. This current outbreak was completely predictable. The CDC didn’t blame the un-vaxed in 2006, or any other year, so why start now.

          • Chris

             /  November 5, 2010

            So why do you not want to give your kids and yourself an at least 80% chance of being protected with the DTaP or Tdap? What exactly are the odds of a bad reaction to getting the pertussis.

          • Chuck

             /  November 5, 2010

            What are the odds of being exposed to it in the first place and what can you do to reduce those odds without being vaccinated?

          • Chris

             /  November 5, 2010

            Right now if you live in California, especially in areas of low vaccine uptake, you have about a 100% chance of getting pertussis if you are not vaccinated.

            If you are vaccinated and live where there is very little vaccine uptake, then it is about 20%.

            If you are vaccinated in live in an area of high vaccine uptake the chances are about 0%.

            If you are not vaccinated, and live in an area of high vaccine uptake, then your chanced of getting pertussis is greater than zero. You are also a societal leech, being a parasite on herd immunity. Not a good thing.

            Seeing how you seem to be afraid of any kind of science, and vaccines… you are more likely hanging around like minded people. Perhaps sending your kids to a school with lax vaccine requirements. Perhaps a Waldorf School (which are usually full of little walking petri dishes). I would say at some point, pertussis will hit your family.

            Good luck with that.

  4. Your ability to move goalposts, invoke nirvana fallacies, and generally write obtusely is riveting.

    • Chuck

       /  November 5, 2010

      No goalposts have been moved and until vaccines are 100% effective and 100% safe (a nirvana fallacy) no perfect solution exists. Until that time does happen, individuals must make decisions based on imperfect information in an imperfect world.

      There are always 2 types of errors:
      Type I: Taking a vaccination and being harmed by it (adverse reaction or vaccine failure and contracting the illness and potential complications)
      Type II: Not taking a vaccine and contracting the illness and potential complications.

      There is no way an individual can control for Type I. Either the vaccine is a match or it isn’t. The individual can tolerate the vaccine, or they cannot. Type I errors are completely external to the individual

      Type II errors are completely under the control of the individual. They can be controlled. Eat well, sleep well, and take care of your health. Know about the general risks of any contagious illnesses and know how to minimize those risks and proactively do so vigilantly. Even if you think you may be sick, be sure to never put others at risk. This is all common sense.

      Type I errors are science’s fault. Type II errors are individuals fault. An individual that experiences a Type I error and sickens another individual is still individually at fault.

  5. MB

     /  November 5, 2010

    Another possible explanation is crappy insurance plans. A good friend of mine recently had a baby, and was horrified to discover that well-baby visits and vaccinations weren’t fully covered on her insurance plan. She is a full time employee of a large university. One with a medical school and hospital system, just to add to the hilarity. Considering that ‘maternity leave’ in the USA often consists partly to mostly of unpaid FMLA, this can become a financial burden for those families in the employed but pinched situation. Luckily she and her family were able to cover the extra expense, but I can imagine a lot of situations occuring in the past couple of years where parents might make a decision based in part on out of pocket expense.

  6. Chuck

     /  November 5, 2010

    Chris,

    1) “Right now if you live in California, especially in areas of low vaccine uptake, you have about a 100% chance of getting pertussis if you are not vaccinated.”

    CDC:
    “From January to November 2, 2010, more than 6,400 cases of pertussis (including ten infant deaths) were reported throughout California. This is the most cases reported in 60 years when 6,613 cases were reported in 1950 and the highest incidence in 52 years when a rate of 26.0 cases/100,000 was reported in 1958. Previously, the peak was in 2005 when there were 3,182 cases reported.”

    So there are only 6,400 unvaccinated individuals in all of CA.
    Your assertion on this fact: FAIL

    2) “If you are vaccinated and live where there is very little vaccine uptake, then it is about 20%”

    I remember seeing some geographic chart (somewhere, maybe even WCU) that showed that Washington State had the highest percent of population un-vaxed.

    As of September 2010:
    “Since July, the Clark County, Wash., health department has investigated 38 cases of the illness also known as whooping cough. Of those, 25 are confirmed, five are probable cases and eight are suspect cases.”

    Doing much better (<1%) of CA cases

    If someone has better information concerning concentrations of un-vaxed populations or the number of pertussis cases in Washington, I will defer to their information.

    Until that time Your assertion on this fact: FAIL

    3)” If you are not vaccinated, and live in an area of high vaccine uptake, then your chanced of getting pertussis is greater than zero. You are also a societal leech, being a parasite on herd immunity.”

    CDC:
    http://www.cdc.gov/vaccines/vac-gen/whatifstop.htm#pertussis
    “Since the early 1980s, reported pertussis cases have been increasing, with peaks every 3-5 years; however, the number of reported cases remains much lower than levels seen in the pre-vaccine era. Compared with pertussis cases in other age groups, infants who are 6 months old or younger with pertussis experience the highest rate of hospitalization, pneumonia, seizures, encephalopathy (a degenerative disease of the brain) and death. From 2000 through 2008, 181 persons died from pertussis; 166 of these were less than six months old.”

    Children who are 6 months old are unvaxed and are not societal leeches.

    A different CDC document says that between 1996 and 2006 (the report was released in 2007) there were 131,867 confirmed pertussis cases with DTP3+ coverage averaging 95.3%. If 95% isn’t herd immunity, then what is? If 95% is “herd Immunity” then are these just acceptable losses? The document doesn’t differentiate if the cases were in the vaccinated population or unvaccinated population. I would think that they would want to prove their point concerning the effectiveness of vaccination.

    95.3% coverage Good luck with that.

  7. 131,867 is over 10 years. Before vaccination there were that many cases every year. From your CDC link:

    “Before pertussis immunizations were available, nearly all children developed whooping cough. In the U.S., prior to pertussis immunization, between 150,000 and 260,000 cases of pertussis were reported each year, with up to 9,000 pertussis-related deaths.”

    131,867/10 = 13,187 cases per year compared to 205,000 per year pre-vaccine (average of 150,000 and 260,000). 181/8 = 23 deaths a year compared to 9,000 pre-vaccine. If 95.3% coverage only reduces the number of cases by 191,813 and saves 8,987 lives a year, that sounds pretty good to me.

    Because it didn’t reduce cases and deaths to zero we should go back to 200,000+ cases and 9,000+ deaths? Is that actually your argument?

    • yes, but expect him to deny it and change the topic while running wildly with the goalposts in hand.

      • Chris

         /  November 6, 2010

        He must get very tired moving those goalposts. I figure he must be halfway across his state by now.

        I wonder if he is related to a certain thing at SBM.

    • Chuck

       /  November 6, 2010

      Let’s discuss CDC statistics, Daedalus, shall we.
      I picked one document that contained both documented cases and corresponding vaccination rates. Admittedly the documentation did contain more data, but since I had to re-key all the data, I only select the most recent 10 years to illustrate what the modern medical community is capable of doing today.

      What years did the 150K and 200K cases that you used in your calculation come from? Was the 9K in deaths inside or outside the time span where the number of cases you cited occurred? Do you know anything about the statistics you used at all or how accurate they are? The CDC has told the medical community to stop using the 36K deaths per year for influenza because that statistic was wrong.

      Admittedly, I also did not pull in the number of deaths for 1996-2006. I would believe that you pulled the number of deaths from the same document . I don’t know why you couldn’t add up 10 numbers instead of 8 so we could see all the facts for the time frame I picked.

      There was a reason to not include the number of deaths in a discussion concerning herd immunity and vaccine effectiveness. The number of deaths is a direct function of the technology and medical skills of the time being researched. The skills, or lack thereof, that would save a sickened individual is a completely different topic.

      You do however use a post hoc ergo propter hoc fallcy in your apples to oranges comparison of pre-vaccine statistics to post-vaccine statistical analysis. Can you statically prove that the reduced number of cases is ONLY because of the vaccine and nothing else? Just because an individual is vaccinated doesn’t guarantee that they won’t contract an illness and just because an individual isn’t vaccinated doesn’t guarantee that they will contract an illness. Your statistical 8,987 lives saved all contracted pertussis. They just didn’t die. The spaghetti monster saved them all, didn’t he Daedalus?

      • Chuck

         /  November 6, 2010

        “. I would believe that you pulled the number of deaths from the same document . I don’t know why you couldn’t add up 10 numbers instead of 8 so we could see all the facts for the time frame I picked.”

        I apologize Daedalus, I now see where you got your data from after a good night’s sleep. However it is from a different time set that the information I retrieved. From a medical analysis standpoint of my data, that would be a statistical fail.

        I will be more than happy to retrieve that data on Monday since it is back at my office and I have a weekend to enjoy. I hope you also have a very good weekend as well.

        • HAHAHAHAHAHA!!

        • Chuck,

          I don’t need statistics to compare 23 deaths a year with 9,000 deaths a year.

          I don’t need statistics to compare 205,000 cases a year with 13,000 cases a year.

          Your problem is that your default idea is that vaccines don’t prevent disease and that vaccines don’t decrease death rates. There is no data or theory to support that idea, making it not a hypothesis.

          You are attempting to make the “null hypothesis” the idea that “because vaccines are bad, if the case rate or death rate go down then something other than vaccines must have reduced the case rate and the death rate because vaccines are bad”, an idea that cannot be falsified, making it also not a hypothesis.

          Can it be proven that something other than vaccines didn’t make the case rate and the death rate go down exactly synchronous with vaccine usage? No, it can’t. Aliens might have intervened using technology indistinguishable from magic, simply to trick humans into thinking vaccines were effective. I consider that idea to have a sufficiently low prior probability that it can be neglected.

  8. Gaythia

     /  November 6, 2010

    A little off topic, but because you might be tired of talking to Chuck, and because good news is good: Here is a news article on the very high response to a vaccination campaign today at Colorado State University in Fort Collins:

    http://www.9news.com/news/article.aspx?storyid=161931&catid=339

    “With the thoughts of CSU student Christina Adame and three local hockey players lost to invasive bacterial meningococcal disease still lingering among many on campus, about 7,000 students lined up to receive the vaccine free of charge on Friday, making it one of the largest mass vaccination clinics ever conducted in Colorado.

    Friday’s huge demand for the meningococcal vaccine inspired public health officials to hold a second clinic for CSU students and faculty under age 30 between 10 a.m. and 2 p.m. on Thursday.

    In only six days, state and county public health officials marshaled 330 volunteers from 20 counties to conduct the clinic, which was orchestrated with few hitches Friday, said Anne Hudgens, director of the CSU Health Network.

    Each minute during the clinic, 14 people received meningococcal vaccinations. Each hour, 888 inoculations were administered. “

  9. Chuck

     /  November 6, 2010

    Dr. Lipson,

    Serious question

    As an educator, I am assuming that your educated guess would be better than most. I am not asking for a in-depth, peer-reviewed , scientific study. I am asking for your opinion.

    Given every possible reason why any individual would not be immune to a vaccine preventable illness, which illness (es) are not at a “herd immunity” threshold for that illness? (other than influenza because we both know why)

    • Can you re-word that into a question that makes sense?

      • Chuck

         /  November 7, 2010

        What vaccine preventable illnesses have enough of the population that are truly immune to generate herd immunity?

        • GoatRider

           /  November 7, 2010

          I’m not entirely sure I understand your question yet, but I think “Smallpox” is one answer.

          • and measles, mumps, rubella, polio…

            the problem is that chuck will now pick up the goalpost and tell us all that because there are still monkeys diseases, three isn’t really herd immunity.

          • Chuck

             /  November 7, 2010

            It is impossible for me to pick up a goal post if one is never planted in the ground.

            I am truly sorry that I asked you a serious questiona and actually expected to get a serious answer.

            I hhave to now guess that herd immunity is actually a nirvana fallcy that is never achievable.

          • Chuck

             /  November 7, 2010

            Mathematical formula:
            100% – % of population who are not/cannot be vaccinated – % of population who have been vaccinated but are not immune (1-effective rate)-% of population who have been vaccinated but immunity has waned – % of population who have become immune compromised-(any other variables an immunologist would know that I may not)

            What vaccine preventable illnesses have the result of that formula above the necessary threshold to maintain herd immunity?

            I don’t know if the population is still immune to Smallpox, but I would hope that that is just a science fiction question. Smallpox was eradicated, but that vaccine did have the highest number of adverse reaction (I’m sure PAL will correct me if that statement is wrong)

          • QED.

            Where do you get these formulas?

          • Chuck

             /  November 7, 2010

            I am really trying to be serious, and you make it very difficult. I really hope for the sake of your patients, that you are not like this with them.

            The formula is my educated guess as to what percentage of the population defines herd immunity.

          • That’s not the correct formula, Chuck. Herd immunity is exactly what protects those who are immunocompromised, or in whom vaccination didn’t “take,” etc. Herd immunity is much more dependent on the R0 (transmissibility) of the pathogen, and the mode in which it is spread, than the simple immunological characteristics of the population. For example, measles is incredibly infectious, and spread by droplets, so we need a very high proportion of the population (up to ~90-95%) to be vaccinated in order to keep this pathogen in check. Similarly for pertussis, which is complicated because immunity does wane and so booster shots are necessary. For a pathogen like polio, which has a fecal-oral route (and therefore makes it a bit more difficult to transmit), it’s more like 80-85% of the population that needs to be effectively vaccinated in order for herd immunity to work. For something like flu, because of its constant evolution, “herd immunity” is short-lived and local (eg by getting vaccinated, you will help to protect your family, patients etc. but it won’t do a whole lot to reduce the burden of influenza in the population as a whole, since vaccine uptake overall is just too low).

            Did that help to answer your question?

          • Chuck

             /  November 7, 2010

            Thank you for your intelligent response, which I was hoping to get from PAL.

            I assumed that herd immunity would be different based on transmissibility and how infectious each illness is. I asserted in my request to Dr. Lipson that I already knew influenza wasn’t at a herd immunity level just from the vaccination rates alone.

            I would hope there is a “goal post” for each illness to define if herd immunity is currently being maintained. Given the dynamic nature of immunity, waning of immunizations, sicknesses or medical treatments that reduce immune responses, just knowing the vaccination rates and effective rates is not enough information to determine if herd immunity is being maintained.

            A 100% herd immunity is theoretically impossible just given effective rates of vaccines. So a 93-94% herd immunity would be the upper limit and 80% would be the lower limit. Once you drop below that lower limit there are no free rides and it becomes more and more an “every man for themselves” situation like we currently have for influenza.

            I appreciate your response.

        • Chuck, “herd immunity” (HI) is about blocking transmission, not about preventing each and every case of disease. As Tara said, it is about reducing the transmission.

          Suppose we have a disease which is highly transmissible, so that virtually everyone who is exposed gets the disease if they are not immune or vaccinated. Suppose there is a vaccine that is 80% effective (VEF), that is if 5 vaccinated people are exposed to the disease, 4 won’t get it, but one will. Suppose that each infected person will expose the disease to X more people who will or will not get the disease depending on their immunity status.

          What is necessary for herd immunity (HI) to be effective is for the number of new cases (NC) to be less than one. This happens when the number of susceptible people (1-(HI)*(VEF)) exposed per case (X) is less than one, or when X*(1 – (HI)*(VEF)) is less than 1.

          If X people are exposed, then for the epidemic to not spread we need NC less than 1, or for

          (HI)*(VEF) to be greater than (1 – 1/(X)). For the case of VEF = 0.8, then

          For X=4.5 (something smallpox like), HI needs to be greater than 0.972

          For X=4 (something measles like), HI needs to be greater than 0.9375

          For X=3, HI needs to be greater than 0.8325

          For X=2, HI needs to be greater than 0.625

          If you have a high X and a low HI, then the epidemic will spread until the HI becomes high enough to block transmission, either through vaccination, or because a large enough fraction of the population has gotten the disease and is now immune.

          Because exposures and susceptibilities are not continuous functions, these are just approximations. If you increase the vaccine effectiveness, the HI necessary to prevent transmission goes down. If you reduce exposure, HI needed goes down too. There are trade-offs among these, and the actual numbers are idiosyncratic to each individual and can’t be tested or predicted.

          • Also, remember that herd immunity is not the only goal of vaccination. Vaccination of each individual is meant to prevent or mitigate disease in that individual, as in the case of flu vaccines where herd immunity is less relevant.

          • Vicki

             /  November 7, 2010

            Indeed. That my flu vaccine may help protect my partner’s niece (who cannot get the vaccine because she has an egg allergy) is nice, but it’s not the main reason I got vaccinated.

          • Chuck

             /  November 7, 2010

            Daedalus,

            I like to be able to determine ranges of variable in formulas in order to determine all potential outcomes.

            A real word calculation with a vaccine with a 95% effective rate, 99% of the population vaccinated, (1% not being able to be vaccinated, then the calculation would look like this:

            (1-.94)*(VEF)>1-1/X

            Correct?
            Question 2: What is VEF and how is it determined?

          • For your example,
            VEF = 0.95
            HI = 0.99

            The calculation is then (0.95)*(0.99) is greater than (1-1/X)

            0.9405 is greater than (1-1/X)

            Solving for X, X is less than 16.8 for the epidemic to extinguish. At 8 weeks at X=16 the number of cases per original case is 0.71. At 8 weeks at X=17 the number of cases is 1.08, still expanding but very slowly.

            At X=16 and both HI and VEF at 0.95, the 8 week number is 22.5.

            At X= 16 and both HI and VEF at 0.90, the 8 week total is 2400.

            At X= 16 and both HI and VEF at 0.80, the 8 week total is 2.1×10^5.

            In a totally naïve population (HI and VEF =0), the 8 week total is 2.68×10^8, essentially the entire US population (16^7). The model breaks down at these levels because the number of naïve individuals that can be infected does not stay at such a high number.

            VEF is what fraction of vaccinated people get the disease when they are exposed. This is not a hard and fast number, it depends on a lot of things that are unique to the individual, the circumstances under which the vaccine was given and the vaccine itself and what kind of an exposure they had. Usually more vaccine gives a stronger VEF but also more side effects. The immunity doesn’t appear all at once, and then doesn’t stay constant.

            You can’t actually measure that number in people for something that is harmful because it is unethical to expose people to something that might harm them, even if they have been vaccinated. You have to rely on “natural” experiments, where part of the population is vaccinated and an epidemic hits the population. Then you can look at the unvaccinated cases and determine a rough exposure to everyone, and then look at how many vaccinated cases there were out of the total vaccinated population.

          • Chuck

             /  November 7, 2010

            I’m sure you understand why I picked these numbers. This is the absolute best that any vaccine can currently reach.

            Thank you for your explanation.

          • Yes, and you see that with those levels an epidemic that would completely encompass the country in a few weeks can be stopped dead in its tracks, but that even lesser vaccines and lesser herd immunities can still have great value in preventing disease transmission and work synergistically with reductions in transmission via infection control (that reduces the X).

  10. Chuck

     /  November 7, 2010

    While I was trying to research the formula Daedalus provided, I can across an economic model that encompassed the herd immunity calculations into a diminishing marginal return economic model. Coincidentally, the point at which it is impossible to achieve any additional economic benefit from vaccination is the point at which you have achieve the calculated herd immunity. Intuitively it does make sense. No one can buy additional vaccine effectiveness, you can only create a better vaccine. From a societal viewpoint, herd immunity is good enough.

  11. Gaythia

     /  November 7, 2010

    Chuck says “I like to be able to determine ranges of variable in formulas in order to determine all potential outcomes. ”

    That expectation seems over the top. But I do think that distinctions in populations or herds can be drawn because some members of populations or herds are more significant than others. And, I believe that we should note that formalistic health care decisions are being made. I think that we should be better informed as to the validity of these decisions and the extent to which they are driven by economics.

    If one wants to reduce whooping cough deaths in CA for example, it would seem far more effective to focus on immunizing parents, grandparents and caregivers of newborn babies in the Central Valley than it is to worry about some anti-vaxxer parent in a wealthy suburban community. Although, I do believe that it is important to educate the public on the general public obligation for vaccines, because in addition to actually getting vaccinated, some of those wealthier parents ought to be paying higher taxes to cover improved public health care.

    I once got in a dispute with a well known HMO which had decided that due to shortages (greater expense?) of tetanus vaccine they had a policy that year of postponing childhood boosters shots. Which they seemed to be doing without consideration of either individual existing immunity or possible exposure. Being a complaining parent worked, although that is not necessarily the same thing as awarding the scarce vaccines to those with the greatest need.

    The recent Fort Collins bacterial meningococcal disease deaths (see my comment above) seem to be raising interesting issues about the survival of this bacteria in the cold damp environment of ice rinks. So, perhaps there is a greater need for people who spend time colliding with other people in ice rinks to be immunized for this disease as opposed to those who hang out by themselves on desert islands. At any rate, it has taken the county and state public health departments over 4 months to come up with a general immunization program in Fort Collins, and they are not, as yet at least, doing so elsewhere.

  12. Gaythia

     /  November 7, 2010

    Tara C. Smith has a pointer on her blog (Aetiology) to an informative website called “History of Vaccines” which is a project of the College of Physicians of Philadelphia . For those who prefer graphics to formulas, their animated depiction of herd immunity is here: http://www.historyofvaccines.org/content/herd-immunity-0

    • Chuck

       /  November 8, 2010

      The Successful Herd Immunity animation looks like it has the vaccine at 100% effective, but the others look good.

      • Gaythia

         /  November 8, 2010

        Play it again, Chuck!
        What you said above is simply not true.

        On the successful herd immunity animation, 2 healthy (blue) critters remain outside the immunized herd. AND, if you read the caption, it very carefully explains that herd immunity may begin to be induced with as little as 40% of the population vaccinated, but for some diseases, vaccination rates may need to be as much as 80-90%. In the first, unvaccinated animation, they also take care to explain that susceptibility to disease depends on the individual immune system, and indeed, they show some blue healthy critters remaining after the disease runs through the population. And they also have a third animation, demonstrating an unsuccessful attempt at herd immunity. Again, some critters do fine anyway.

        A demonstrations with scientific accuracy and cuteness all at the same time! Of course, they are not specifying the critter, the disease, or the vaccine.

        • Chuck

           /  November 8, 2010

          The blue critters are unvaccinated, the green critters are vaccinated, and the red critters are sick. No one goes from green to red in either of the herd animations. Don’t worry about it.

  1. Obfuscatory Vaccination Math | Good Math, Bad Math
%d bloggers like this: