Paunio M, Peltola H, Valle M, Davidkin I, Virtanen M, Heinonen OP. Department of Public health
, University of Helsinki, Finland. Explosive school-based measles outbreak: intense exposure may have resulted in high risk, even among revaccinees
. American Journal of Epidemiology 1998 Vol. 148, No. 11: 1103-1110
Even high levels of measles vaccination coverage have not always prevented outbreaks of measles spread by airborne transmission. It has been suggested that a large inoculum might increase vaccine failure risk. Airbome transmission might occasionally entail a large measles inoculum. The epidemiologic relevance of measles among properly vaccinated persons (i.e., those vaccinated after 15 months of age and with live attenuated virus) is increased when they become contagious. The authors studied inoculum intensities as measured by proxy variables and the contagiousness of properly vaccinated persons who contracted measles among 51 measles patients infected in one school, at home, or elsewhere, utilizing preexisting records of measles cases and 214 healthy controls from an explosive school outbreak that occurred in a rural Finnish municipality in 1989. One "super-spreader" infected 22 others in one day, including eight once-vaccinated students and one twice-vaccinated student, probably during an assembly of 144 students in a poorly ventilated hallway with no sunlight. Those infected later at home had high measles risk, even if they were revaccinees. When siblings shared a bedroom with a measles case, a 78 percent risk (seven out of nine children) was observed among vaccinees. Vaccinees had approximately 2 days' shorter incubation time than unvaccinated persons. Vaccinated and unvaccinated students were equally able to infect their siblings. Total protection against measles might not be achievable, even among revaccinees, when children are confronted with intense exposure to measles virus.
In this outbreak, an attempt has been made by the authors to blame this "explosive outbreak" to an "intense exposure" to a measles inoculum and the existence of a "super-spreader". Bottom line is revaccination does not prevent measles, and quite how you can establish an "intense exposure" is not scientifically validated as a reasonable explanation - its speculation. Vaccinated and unvaccinated students were equally able to infect their siblings. So vaccination does not prevent the disease, nor does it prevent the transmission of disease through the vaccinated. Being "vaccinated" does not equate to being "immunized" - read it here, they are two separate things, despite the fact that "immunization" is used in the mass-marketing of vaccines.