Vaccines -- Digging for Data

Many parents are concerned about the safety of vaccines these days, especially the influenza and the MMR vaccines. So it seemed like a good time to offer some solid sources of information on this timely topic.

Before examining the vaccines themselves, it's worth taking a look at the illnesses these vaccines target. Vaccine safety has become an issue because this country has not experienced any outbreak of life-threatening childhood disease since the eradication of polio. The last few polio survivors are now so elderly and the disease is so unknown that almost all physicians in this country are unfamiliar with its treatment. NPR told the story of one 73-year-old physician and polio survivor who has specialized in the disease and feels unable to retire because there is simply no one to replace him. Few people can remember the terror produced by the annual return of polio when parents would fear for their children's lives. Each year new children would add to numbers in wards those encased in iron lungs or left paraplegic by the disease. Even fewer can remember the Great Influenza Outbreak of 1918, which devastated whole families in many areas of the country. We even tend to forget that measles is not "just some childhood disease" but remains a leading cause of death in young children in areas of the world where significant populations are not immunized. We live, whether we acknowledge it or not, in a very healthy time and place. For an even greater sense of this, check out the 10 Worst Epidemics on HowStuffWorks.

Our overall health has allowed us to focus on the potential risks of vaccines rather than the diseases for which they were developed. This is the focus of Amy Wallace's article in Wired, for which she has received a lot of villification as well as support. As she discusses in the article, much of the difficulty for science in the discussion is the difficulty scientists have talking in absolutes. It operates in a world of probabilities and numbers, worlds in which people are often uncomfortable -- but which continue to support the value of vaccination. For example recent studies underscore the importance of pregnant women receiving the flu vaccine. While the World Health Organization, which tracks measles deaths around the world, which many in the U.S. might be surprised to know numbered around three quarters of a million in 2000 dropped by 74% by 2007 strictly as a result of vaccination programs. The percentages of people choosing to take vaccines in the U.S. remain low, as reported by the Centers for Disease Control. Here is the 2008 data. The reasons people give for not vaccinating vary, as do the people who make the choice, as highlighted in this NY Times article.

Autism spectrum disorders and any potential relationship they may have to vaccines have been a chief point of concern for many parents. The CDC addresses these concerns explicitly on their site. Autism Speaks, one of the foremost autism research organizations also addresses these issues, explicitly pointing out that it fully supports immunization programs as "one of our nation's most effective programs for preventing serious infectious diseases", an issue of no less concern to parents of autistic children. At the same time, it takes parents concerns about possible links between autism and vaccines seriously and continues to support research exploring possible links between specific genetic and environmental links (such as vaccines).

Another concern expressed by parents references the number of vaccines administered to infants and young children. Again, the CDC addresses this concern. The American Academy of Pediatricians provides even more detailed information regarding the vaccine schedule and the importance of immunizing children. PKIDs, Parents of Kids with Infectious Diseases provides information garnered from the CDC about what would happen if too many people start opting out of immunization programs. This organization consists of parents who deal with the reality of the effects of infectious disease on a daily basis. But perhaps the best overall information for parents or anyone concerned with vaccine safety can be found on the site of the Children's Hospital of Philadelphia's Vaccine Education Center. This site explains how vaccines are evaluated for safety, explains why children would benefit from vaccinations from something like hepatitis B that seems like an adults' disease and answers every other question raised in this blog as well. Now, in the name of openness, I should point out that the demon of the anti-vaccine movement, Paul Offit works at CHOP and signed off on the site's answers.

This leads to the final point. The anti-vaccine movement is largely led by a group of highly vocal advocates. The most famous is GenerationRescue and its "research arm" FourteenStudies. But these sites do not meet the standards of quality met by the others referenced earlier, despite their efforts to appear to do so. For a good analysis of FourteenStudies failure to do so, read Mark Crislip's analysis of the study evaluations on FourteenStudies on the blog Science-Based Medicine. Similarly Medical Veritas, a peer-reviewed medical journal frequently cited by vaccine opponents as a source of "good" studies, must be regarded as a fringe journal, so much so that its contents are not included in PubMed, the standard tool for medical research. (An interesting discussion of the reliability of the journal can be read on this Wikipedia editorial page.) For a look at DACC's standards of web site evaluation, see this list.