Tuesday, July 15, 2008

To Vaccinate or Not to Vaccinate. Is that really the question?

When I had my son, it didn’t occur to me to look into the potential side effects of vaccines outside of how they might impact his sleeping and eating for the next three days. It was hard enough to just get him to the doctor, comfort him and reapply my make-up to hide the streaks my tears left before returning to work. At the time the vaccine autism debate was ongoing and highly debated online and overseas but it had not yet been embraced by the national media, nor did it have celebrity spokespeople.

Recently, a close friend asked me if I had my son vaccinated.To which I said of course. Then she told me about the fierce debate taking place online in community sites in Brooklyn and elsewhere. I started following the debates and ultimately started looking into the research myself. While I am by no means an autism expert or a Public Health scientist, I did get half way through my Masters at Columbia’s School of Public Health before life happened (read: I met my husband moved to San Francisco and started organizing conferences for healthcare executives instead of actually becoming one myself). That said, I can still get through a scientific paper and when I started looking into the autism and vaccine debate the basics I learned in those first couple years at Columbia came back very quickly.

At its core, the vaccine autism debate surrounds the use of thimerosal in vaccines. Thimerosal is an organo-mercury compound (approximately 49% mercury by weight) used to prevent bacterial infections in multi-dose injectable drugs. Despite a lack of conclusive evidence that it was harmful, thimerosal was removed from all pediatric vaccines in 2001 with the exception of the influenza vaccine.

After weeks of research, I’ve found nothing but correlational evidence and personal testimony that there is a link between autism and vaccines. If there is anything that my studies in epidemiology taught me, it is that correlation does not imply causation. So while there is certainly some evidence out there that suggests that the scientific community should explore ways to create safer and more effective vaccines for our children, there is nothing definitive that says that vaccines are dangerous.

What I do know without a doubt is that infectious diseases like the flu and measles kill children and fewer vaccinated children increases the number of disease related deaths. In the 2007-2008 flu season 83 children under the age of 18 died of the flu. In 2006-2007 68 died and in 2005-2006 35 died. The numbers of childhood flu related deaths are on the rise and this does not include the numbers that were hospitalized. During the 2007-2008 season of those dead 58 had not received flu shots and 25 had. As it happens the 2007-2008 vaccine batch was not a very good match for the flu, however if no one received the vaccine the numbers would be devastating.

What prevented a serious outbreak is something called herd immunity. What many parents engaged in this debate don’t seem to understand is that immunization is a public health necessity and without it we would all be dead. The theory of herd immunity is based on the fact that the more immune people there are in a community the harder it is for a disease to spread. The fact is that vaccines don’t work 100% of the time and that is ok. They only need to work on a certain percentage of the population to prevent the spread of disease. What is required to prevent the spread of disease is that the population reached the immunity threshold.

You see the spread of infectious disease is a numbers game…it starts with what is called the basic reproduction number which tells you how contagious a particular disease is. This is the number of people that will get the disease from one infected individual absent any intervention. For measles this number is between 12-18 and for the flu it is between 2-3, so the measles is almost six times as contagious as the flu. After the basic reproduction number, the other very important number is the number of people not immune to the given disease. Other factors must also be considered, however the biggest factor in determining the threat of a pandemic is the number of people not immune which is why it is an absolute imperative that when a vaccine exists for a deadly infectious disease as many people as possible be vaccinated.

According to the CDC in 2008 between January and April 64 people contracted measles, 14 of them babies too young to receive the vaccine. While measles remains rare in the U.S., 20 million people a year (311,000 children in 2005) contract measles worldwide, so if our herd immunity is weakened an epidemic is just a plane ride away. Yet the CDC reports that a quarter of children in the U.S. were not being vaccinated despite the fact that scientific evidence provides no support for the hypothesis that vaccines are linked to autism. In England where the debate is even more heated than here, there were 971 cases of measles in 2007, the largest number since records began in 1995.

When I began researching this topic, I approached it in much the same way as I did BPA and pharmaceuticals in the water. I was looking for a wrong and a right answer, someone to blame for misinformation and an alternative solution, but what I realized was that this is just not that simple. If BPA might be bad for you, use products without BPA. If tap water might contain harmful contaminants, filter it or use bottled water. If vaccines might cause autism, definitely still vaccinate because not getting vaccinated kills people. While researchers work to determine the safety and find safer alternatives, we as responsible parents must continue to vaccinate our children. The question is not whether we should vaccinate or not or whether vaccines are linked to autism. The question is why do we vaccinate our children and the answer is to prevent millions of deaths each year.

Questions We Should Be Asking

Do our friends, families and politicians understand the concept of herd immunity as it relates to vaccines?

Can pediatric vaccine schedules be revised to minimize potential risk?

Can pharmaceutical companies develop safer vaccine additives?

What do our pediatricians think regarding the safety of current vaccines and vaccine schedules?

Will our pediatricians minimize the number of vaccines our children receive at each visit?

Given the volatility of this debate, I probably don’t need to invite comments, but as I am always interested in what others know and are thinking about, I welcome you to share your thoughts.


Anonymous said...

Hallelujah and AMEN! I am a physician and a mom and would never dream of not vaccinating my daughter. This is a critical public health issue as you so adeptly explained in your blog. There has never been any solid evidence that there is a link between autism and vaccines. The scariest part of the anti-vaccine movement as you pointed out, is that another's decision to not vaccinate affects everyone.

I bet that if we were lucky enough to develop a vaccine against HIV, all the anti-vaccine parents would be first in line to give it to their kids. Why? Because our generation has experienced the AIDS epidemic and would want to prevent it. I guess if you are not familiar with the history of public health and medicine one would not be aware of the morbidity and mortality caused by the viruses and bacteria we vaccinate against.

maceo said...

No link? But I read it on the internets.

Unfortunately I think this is one area where the internet falls a little short.

Everyone is going to do their research and read 100 conspiracy sites implying a link.

One lone authoritative site (e.g. cdc.gov) might speak to the contrary. They have the platform, but not the numbers.

Unfortunately one thing the interwebs are good at is giving equal time to 100 conspiracy theorists.

And score one for the echo chamber.

Heather said...

Thank you so much for this post! I'm no scientist, I came to the same conclusions you have: it's mostly circumstantial evidence and personal testimony.

Anti-vaxers also like to debunk major studies that show there is no link between vaccines and autism, but they tend to throw out the baby with the bathwater--discount all the results of a reputable study based on a minor procedural error or statistical anomaly.

And many are now blaming aluminum, another vaccine preservative. That doesn't seem right to me--aluminum is in everything. You probably get more exposure to aluminum in Coke cans and toothpaste than in any vaccine.

Anyway, bottom line to me: it's possible that vaccines might have some as-yet unknown link to autism, perhaps through prior susceptibility, but I've not seen anything to convince me yet. But communicable diseases are a definite threat to everyone, so I'm getting my kids the shots.

And it really, really worries me how many outbreaks of measles we're seeing--that's the most communicable of the diseases we vaccinate against, and often the first to break out in anti-vax communities.

Anonymous said...

Really excellent post and very well said. I have vaccinated all 3 of my children according to schedule because I believe the benefits of the vaccines outweighed the potential risks. Personally, I don't believe autism is caused by vaccines, especially based on the research thus far. I do think, however, that it is possible that something in the vaccines may trigger the onset of autism in someone genetically predisposed to it. Obviously more research needs to be done as the rates of autistic children continue to increase. There is a great debate on this topic at www.opposingviews.com/questions/are-autism-and-vaccines-linked Experts from both sides debate the issue, and there is a guy named Kevin Leitch who is really taking on the groups who believe autism and vaccines are connected. Very informative read and discussion on the issue!