Thursday, May 13, 2010

The Myth of Herd Immunity


When the vaccine religionists sneer about those who are atheists of their religion, one specious, completely unsupportable, argument they regularly parrot is that those who do not vaccinate are benefiting from "herd immunity", i.e. the fictional notion that if a minimum number of people are vaccinated, it will provide protection to the entire herd (never mind that they are referring to human beings as a herd).


But what if "herd immunity" is a myth? From the horse's mouth, none other than the New England Journal of Medicine -


Measles outbreak in a fully immunized secondary-school population
TL Gustafson, AW Lievens, PA Brunell, RG Moellenberg, CM Buttery, and LM Sehulster

An outbreak of measles occurred among adolescents in Corpus Christi, Texas, in the spring of 1985, even though vaccination requirements for school attendance had been thoroughly enforced. Serum samples from 1806 students at two secondary schools were obtained eight days after the onset of the first case. Only 4.1 percent of these students (74 of 1806) lacked detectable antibody to measles according to enzyme-linked immunosorbent assay, and more than 99 percent had records of vaccination with live measles vaccine [in other words, 100% vaccination].


Stratified analysis showed that the number of doses of vaccine received was the most important predictor of antibody response. Ninety-five percent confidence intervals of seronegative rates were 0 to 3.3 percent for students who had received two prior doses of vaccine, as compared with 3.6 to 6.8 percent for students who had received only a single dose. After the survey, none of the 1732 seropositive students contracted measles. Fourteen of 74 seronegative students, all of whom had been vaccinated, contracted measles. In addition, three seronegative students seroconverted without experiencing any symptoms.


We conclude that outbreaks of measles can occur in secondary schools, even when more than 99 percent of the students have been vaccinated and more than 95 percent are immune.

***

From the Archives of Internal Medicine -

Failure to Reach the Goal of Measles Elimination
Apparent Paradox of Measles Infections in Immunized Persons
Gregory A. Poland, MD; Robert M. Jacobson, MD

Methods

We performed a computerized bibliographic literature search (National Library of Medicine) for all English-language articles dealing with measles outbreaks. We limited our search to reports of US and Canadian school-based outbreaks of measles, and we spoke with experts to get estimates of vaccine failure rates. In addition, we devised a hypothetical model of a school where measles immunization rates could be varied, vaccine failure rates could be calculated, and the percentage of measles cases occurring in immunized students could be determined.


Results

We found 18 reports of measles outbreaks in very highly immunized school populations where 71% to 99.8% of students were immunized against measles. Despite these high rates of immunization, 30% to 100% (mean, 77%) of all measles cases in these outbreaks occurred in previously immunized students. In our hypothetical school model, after more than 95% of schoolchildren are immunized against measles, the majority of measles cases occur in appropriately immunized children.

Conclusions

The apparent paradox is that as measles immunization rates rise to high levels in a population, measles becomes a disease of immunized persons. Because of the failure rate of the vaccine and the unique transmissibility of the measles virus, the currently available measles vaccine, used in a single-dose strategy, is unlikely to completely eliminate measles. The longterm success of a two-dose strategy to eliminate measles remains to be determined.

So tell me again why I should allow some quack to inject me or my child with nasty ingredients such as (MSG), potassium chloride, potassium phosphate monobasic, potassium phosphate dibasic, sodium bicarbonate, sodium phosphate dibasic, sorbitol, and sucrose, human albumin, human diploid cells, residual components of MRC-5 cells including DNA and proteins, bovine serum, hydrolized gelatin, and chicken embryos.