The CDC recently published robust evidence that supports rotavirus vaccine effectiveness. There is nothing more powerful than epidemiological studies that show a correlation (and causality) between the drop in the incidence of a vaccine preventable disease immediately after wide introduction of a the vaccine itself in a relatively closed population.
Update 1. Added more information about the power of the herd immunity written by Tara Haelle.
One of the most recent and important vaccines added to the current schedule of immunization is the rotavirus vaccine, introduced in the USA in 2007. Before the introduction of the vaccine, rotavirus was the most common cause of severe gastroenteritis in US children under 5 years old. Each year, rotavirus caused an estimated 20 to 60 deaths, 55,000 to 70,000 hospitalizations, and nearly half a million non-emergency visits to healthcare facilities.
A study, recently published the Pediatrics journal, concluded that, after the rotavirus vaccines was introduced, the numbers of diarrhea-related illness in US children dropped significantly. Moreover, probably as a result of herd immunity (where transmission through a population is inhibited by individual who are immune to the disease), the study found that the rate of hospitalizations related to the virus dropped substantially in both vaccinated and unvaccinated children.
The research examined health insurance data from across the USA (except for Medicaid, and a few states that don’t report data) for children under 5 years, cross tabulating various gastrointestinal illnesses with hospitalizations and other medical care. It also compared the same information to the vaccination status of those children. Finally, they gathered data about these illnesses from 2001 through 2006 (before the vaccine was introduced) and 2007-11, to compare hospitalization and other medical facility encounters between the pre- and post-vaccine groups. Continue reading “Why we immunize–protect children from hospitalization for diarrhea”
Vaccine deniers, especially in the USA, use the passive data from the Vaccine Adverse Event Reporting System (VAERS), a system where individuals can report supposed adverse events post-vaccination, to “prove” certain adverse events. The data is considered to be “passive” because the individual reports can be made online, by fax or by mail–real causal events may be underreported and hyped, imaginary issues with no causality, can be over-reported. However, without medical investigations of causality between the vaccination and the claimed adverse events that are reported to the VAERS database, the data have no real value.
Frankly, VAERS can be gamed by those with nefarious intentions. In reality, VAERS is a feel-good system for those who think that there’s a link between vaccines and something terrible, but without an active investigation, the data is just above the level of being totally meaningless. Most epidemiologists know it is valueless. Even the VAERS system itself says that the data cannot be used to ascertain the difference between coincidence and true causality.
Furthermore, there is a background rate for mortality (death) or morbidity (abnormal medical condition), across all causes, irrespective of whether an individual is vaccinated or not, and unless you understand the background rate, the vaccine “mortality” rate has no scientific meaning. In fact, we could provide data that shows anything might cause any adverse medical event, like playing video games leads to prostate cancer, but we would have no evidence of any type of causality whatsoever. Continue reading “Reports of vaccine related effects can be useful”
If you spend any time reading the antivaccination rants, you will hear about all kinds of conspiracy theories, pseudoscience, and scaremongering. Given that there is little scientific evidence that supports their beliefs, they have little choice but invent strawman arguments to make their point. One of the more amusing strategies of antivaccine cult is to claim that diseases were going away before vaccinations. These people believe, without any evidence whatsoever, that diseases like polio, measles, and chickenpox were disappearing because of better sanitation. Or better nutrition. Or something other than what really ended these diseases–vaccines. It’s a historical revisionism of a legendary level.
Admittedly, part of this belief is that people lack the cultural memory of some of these diseases. Few parents born after 1970 would remember classmates who had been stricken with polio. Few would have remember measles, mumps, or other epidemics sweeping through a school. They just don’t remember it, because vaccines introduced in the 50’s and 60’s reduced, and in the case of smallpox, eliminated the disease. Of course, there is evidence that support the theory that vaccines end diseases. But we don’t have to go back 40 or 50 years to show this happens, but we can talk about a disease that has been drastically reduced in the last few years, just because of a new vaccine.