Vaccine Safety: What to Believe?

If you go by the media's reaction to the Institute of Medicine's new report on vaccine safety, the case is closed. Beyond several side effects, none are considered so catastrophic that the CDC should look seriously into revising the program. However, if you really evaluate the report, how can you close the book on vaccine safety? Overall, the committee made 158 conclusions that fell into one of four categories:

• The evidence supports a causal relationship between the vaccine and the adverse event

• The evidence seems to favor a causal relationship, but isn't as convincing yet

• The evidence in inadequate to either accept or reject a causal relationship

• The evidence favors rejection of a causal relationship

Not surprisingly, the vast majority of their decisions — 133 — fell into the inadequate category. That category encompasses cases in which studies show both a potential connection or no connection between vaccines and an adverse event. It also includes cases in which the information simply doesn't exist to make a sound scientific conclusion. They evaluated data from over the last 20 years and almost all of their decisions were inadequate?

Then, when you see studies like the ones we cite below, even more doubt creeps in.

A Positive Association found between Autism Prevalence and Childhood Vaccination uptake across the U.S. Population; Journal of Toxicology and Environmental Health, May 2011
The reason for the rapid rise of autism in the United States that began in the 1990s is a mystery. Although individuals probably have a genetic predisposition to develop autism, researchers suspect that one or more environmental triggers are also needed. One of those triggers might be the battery of vaccinations that young children receive. Using regression analysis and controlling for family income and ethnicity, the relationship between the proportion of children who received the recommended vaccines by age 2 years and the prevalence of autism (AUT) or speech or language impairment (SLI) in each U.S. state from 2001 and 2007 was determined. A positive and statistically significant relationship was found: The higher the proportion of children receiving recommended vaccinations, the higher was the prevalence of AUT or SLI. A 1% increase in vaccination was associated with an additional 680 children having AUT or SLI. Neither parental behavior nor access to care affected the results, since vaccination proportions were not significantly related (statistically) to any other disability or to the number of pediatricians in a U.S. state. The results suggest that although mercury has been removed from many vaccines, other culprits may link vaccines to autism. Further study into the relationship between vaccines and autism is warranted.

Guillain-Barré Syndrome, Influenzalike Illnesses, and Influenza Vaccination During Seasons With and Without Circulating A/H1N1 Viruses; American Journal of Epidemiology, August 2011
The role of influenzalike illnesses and influenza vaccination in the development of Guillain-Barré syndrome (GBS), particularly the role of A/H1N1 epidemics and A/H1N1 vaccination, is debated. Data on all incident GBS cases meeting the Brighton Collaboration criteria that were diagnosed at 25 neurology centers in France were prospectively collected between March 2007 and June 2010, covering 3 influenza virus seasons, including the 2009–2010 A/H1N1 outbreak. A total of 457 general practitioners provided a registry of patients from which 1,080 controls were matched by age, gender, index date (calendar month), and region to 145 cases. Causal relations were assessed by multivariate case-control analysis with adjustment for risk factors (personal and family history of autoimmune disorders, among others), while matching on age, gender, and calendar time. Influenza (seasonal or A/H1N1) or influenzalike symptoms in the 2 months preceding the index date was associated with GBS, with a matched odds ratio of 2.3 (95% confidence interval (CI): 0.7, 8.2). The difference in the rates of GBS occurring between influenza virus circulation periods and noncirculation periods was highly statistically significant (P = 0.004). Adjusted odds ratios for GBS occurrence within 6 weeks after seasonal and A/H1N1 vaccination were 1.3 (95% CI: 0.4, 4.1) and 0.9 (95% CI: 0.1, 7.6), respectively. Study results confirm that influenza virus is a likely risk factor for GBS.

Here's a Baltimore Sun Op-Ed from a vaccine researcher.