Childhood immunizations are among the most scientifically elegant of accomplishments.  While the disease reduction is impressive, there are other issues that impact when and whether people decide to vaccinate.  We now give 30 - 36 shots before children are 6 years old.  Is this too many?  Does it hurt the immune system?  You've likely heard controversies that confuse matters even more...Here are some answers and resources for common questions.  If you're REALLY just here to see the science, skip to the end for: Mercury in vaccines; herd immunity; autism and MMR; immunogenicity; more!  Note: it's not possible that we know everything about vaccines that there is to know yet.  With that said, reading all the evidence below, we know enough to guide anyone that thoroughly explores the issues.

How Immunizing Started

Childhood immunizations began as an attempt to protect a researcher's child from an unstoppable, horrific death. In 1796, Edward Jenner injected pus from a milkmaid with cowpox to his son and others on a hunch it could prevent the deadly smallpox. (Eew!)

Then as now, many diseases dangerous to adults were deadly to children, and smallpox was the specter of the century. It's easier to imagine such an experiment on your own child if you think of Ebola or cancer or even autism marauding our streets in a very contagious but silent form. Everyone knew friends and acquaintances who had been suddenly struck down. That terror of being helpless to prevent losing your child at an early age made smallpox the first-ever government intrusion into private health (via mandated childhood immunizations.)

Current childhood immunization schedules reflect the balance between cost of disease (in lives, hospitalizations, and long term damage) and the cost and hassle of immunizing.

The first infant immunizations attacked diseases that often killed or maimed (polio, measles, whooping cough). Now, recommended childhood immunizations win the trade-off between the cost of immunizing everyone and the cost of life, hospitalization, and nuisance of the diseases.

MOST people don't end up in the hospital with brain swelling or blood infections after chicken pox, but enough do that the cost of the chicken pox vaccine (varicella) was felt to be worth it to society. MOST children don't end up dehydrated and in the hospital after rotavirus diarrhea, but enough do that the vaccine was felt to be worth it.

Why immunize... newborns?

The theory behind newborn infant immunizations is deceptively simple – get 'em before they're exposed. Diptheria, pertussis, hemophilus influenza (Hib), and pneumococcal diseases kill infants disproportionately to older children or adults. Meningitis is the big problem from Hib, pneumonia and blood infections from pneumococcus. Before the HIB vaccine, the rate of meningitis in newborns with fever was about 1/50. Now? Less than 1/1000.

Why immunize... at all?

We're at a place where "herd immunity" keeps most diseases away. Think of a herd of zebras: the group is able to spy predators better than a single zebra, and alerts the herd when danger is near. Stick an unimmunized wildebeest in the middle of the zebra herd, and the sheer size of the herd still protects it even though it's not really a zebra. The immunity of all the other kids keeps disease away from even the unimmunized child... usually.

There are two downsides to the strategy of refusing childhood immunizations and "counting on the community": one is that kids with immune system problems (leukemia, organ transplant) depend on this herd immunity – too many wildebeests and the protection falls apart. The other downside to refusing immunizations is when the disease has an outbreak in your community, or if you travel to a place where the disease exists and you're unprotected.

Choosing not to immunize either yourself or your child MIGHT turn out all right if you stay in the United States and there aren't too many others who choose to do the same. However, just in the last few years three unimmunized infants in the Philadelphia area died of Hemophilus influenza... so the herd is shrinking, and often doctors can't know what's rising in their communities until a few newborns die.  Skipping your own or your child's travel immunizations when traveling abroad is very dangerous, however. 

How vaccines work:

Vaccines present either a killed or a recognizable piece of a bad disease to the immune system. The first time your system sees this disease, it learns to recognize and make antibodies to the pattern of the virus or bacteria presented in the immunization.

Like most things you learn in school for the first time, the immune system remembers for a variable amount of time, then the system forgets. If the pattern is presented again soon enough, the next time your system sees that pattern, the immune system REALLY remembers, and by the third time it rarely forgets. This accounts for the timing of childhood immunizations, and the reason you get booster shots. Most shots are scheduled based on the optimum timing to make sure your immune system remembers the pattern the most.

When you have a primed immune system, a disease is fought off so rapidly you don't get sick at all (in other words, you're IMMUNE.) When the system has never seen a disease before, it takes a while for it to develop an adequate response, and you can get ill while your system learns to fight it off the hard way. Whether it is permanently bad for you to get ill while you learn depends on the risk of the disease.

Immune system overload from vaccines?

The amount of recognizable material in a vaccine is called the antigenic load. When the first vaccine was introduced, the antigenic load was 200plus antigenic proteins. The total load from the first 6 months of shots now is 150 or so antigens.

What this means is that the amount of material your immune system is learning from is very small compared to what it's exposed to getting a regular cold or flu or infected scratch. It's just that the pieces are very specific and they exactly target what your body needs to fight off the most dangerous diseases.

Do vaccines cause autism?

There are plenty of websites which debate whether or not childhood immunizations may cause autism. It's true that the numbers of vaccines in the US have risen since 2000, and so has autism. In that time, though, the number of hybrid vehicles has also increased, as has the consumption of corn syrup and the number of reality TV shows.

In order to prove causality, the problem has to only occur in the presence of the mystery agent, has to go away when the agent is removed, and has to come back when re-introduced. Since you can't look at causal presence or absence of autism in a single child, and regrettably it won't go away, the only way to sneak up on truth is to look at populations.

Thimerosal was removed from vaccines by 2002, but autism incidence continues to increase. Experts think the causes are multifactorial – a genetic susceptibility plus exposure to something or somethings.  The first "scientific" connection between autism and vaccination by Andrew Wakefield in 1998 has been withdrawn as being BAD SCIENCE by the Lancet itself, an almost unprecedented step, and has been denounced by 10 of the 12 authors prior to that. Denmark removed Thimerosal in 1992. If the thimerosal hypothesis were true, autism rates should have remained the same or dropped. In fact, autism rates continued to climb.(Stehr-Green P, 2003. Am J Preven Med 25,101) Similar results were found in other population based studies (Hviid A, Stellfeld M, JAMA, 209, 1763).

For more information with before and after rates in countries which experimented with stopping vaccines, see these articles:
Scientific review with 16 references
This one is a 2010 Update

Here is the CDC's position on autism and vaccines
http://www.cdc.gov/vaccinesafety/Concerns/Autism/Index.html

Why do we REALLY mistrust vaccines?

Number one: we don't see the danger of the diseases, and, number two: plainly put, watching your child get stuck feels wrong.

Think about this: would you give your child a shot to prevent car crashes? leukemia? autism? In many ways, that's the current analogy to what smallpox, polio, and measles used to be. However, if you don't know someone personally who is crippled, sterilized, killed or scarred by disease, it's tough to justify any pain to your child.  These days you are FAR more likely to personally know someone with permanent disability or death from a crash or cancer than from hemophilus influenza or pneumococcal sepsis.  Why?  BECAUSE VACCINES WORK.

Now that most of the diseases we're immunizing for are not on our emotional radar, it becomes the theoretical risk of measles or polio returning compared to the theoretical risk of autism. We don't know any children wasted from polio; we all know someone with an autistic child.

We're a tough society, and 70% of adults don't mind getting shots themselves. There's not much data on how much we mind watching our CHILD get shots, though, and when you're sleep deprived and your whole world is about protecting that tiny little newborn, well... watching them get poked again and again and again has to evoke some primal sensation of concern.

What if immunizations didn't hurt?  Many fewer people refuse rotavirus vaccine, and when polio vaccine was oral it was the least refused by people who selectively immunized. (Salmon D, 2005).  Why?  This is sheer hypothesizing, but it makes sense to either be that watching a baby take a liquid seems more natural than steel, or because shots cause pain.  Perhaps if we focus more on comfort, or ways to give vaccines without needles, we'll have fewer unprotected children.

Mercury: Shots USED to contain trace ethyl mercury as a preservative.  This is metabolized by the body in about ½ weeks, and has not been found to cause ANY health problems. Methyl “Mad Hatter” Mercury, the kind that builds up in fish, is the one to watch.  One tin of tuna contains 3x methyl mercury than the ethyl mercury in a shot. To be consistent, if you’re really worried about mercury, never eat a tuna fish sandwich.

Shots Cause Pain: I totally get that watching your child get stuck feels wrong.  Even Elizabeth Gore, the most pro-vaccine champion, admitted to sending her husband to get her child vaccinated because it was hard to watch.  After all, I invented Buzzy to block the pain of shots that led to my son’s needle phobia. I’d be happy for kids to have fewer shots, via microneedles, more inhaled vaccinations, you name it.  (Besides, since Buzzy works for splinters, IVs, and itching, not worrying about painful vaccinations would be a godsend.)  All that said, research shows doctors and parents feel uncomfortable giving more that three shots at once.  Our NIH data shows increasing distress after two shots, with the most distress at 5 shots no matter what we do.  Since needle phobia forms at age 4-6, and kids age 4 – 4.5 rate a peak of procedural pain, I think an alternate vaccine schedule starting at 5 sounds great.  So does giving some shots at schools to avoid the association of doctors and pain.  A 2012 Anna Taddio study found that 26% of adults and 63% of kids fear needles, and that 8% of parents said it affected their willingness to vaccinate.  The least refused vaccine in a 2005 paper by Dan Salmon investigation of partial immunizers was polio.  Why?  It was ORAL.  Pain matters.  We can do better.

Autism:  The paper than injected this insidious doubt into the world was found to be based on faulty science.  The doctor has lost his license, the Lancet retracted the paper.  Furthermore, population-based studies of countries where MMR rates dropped didn’t find a decrease in autism, they found an INCREASE.  And deaths from measles jumped.  Look, finding a cause and a cure for autism is critical.  We’ve spent enormous amounts of money looking under the vaccine rock.  Let’s spend some engery and time turning over other rocks. 

Herd Immunity:  Vaccine refusal is on the rise, affecting different diseases differently.  Pertussis needs a 94% herd saturation, so we’re seeing a pertussis (whooping cough) epidemic and deaths (and unvaccinated kids are 23x more likely to contract it).  Measles immunity needs less saturation and lasts longer, so only small communities with greater lack of vaccination see outbreaks.  Look back at “shots hurt”, though:  prior to 1983, kids got 6 shots by the time they were 6.  Since 2000, it’s 30 – 37.  A kid who was stung by one bee may not grow up afraid, but a kid stung by 6 may grow up fearful.  In Taddio’s study, fear of needles is tied to unwillingness to vaccinate your children.  Our first cancer-preventing vaccine, HPV, became available to kids born after 2000, of whom 63% fear needles.  HPV is voluntary, and only has a 30-odd% saturation. I don’t think the math is coincidental.  In 10 years when these children grow up, will they drive themselves to the doctor willingly?  Will they immunize their children at the same rates that parents today (born largely before 1983) do?  Just from the 5% or so decline we’ve seen in vaccinating, there are now new outbreaks:  measles 2008, 2011, mumps 2009 (several deaths).  All Hemophilus Influenza (HIB) deaths in 2009 were in unvaccinated children. Pertussis epidemics in 2010 and 2012 have been widely reported.  The herd is thinning.

Immunogenic Load: This is another way of saying “how much does a disease stress out your immune system?”  OK, so imagine a disease is a Harry Potter Lego Hogwarts. You get the disease, and your disease fighting system begins smashing the castle while your immune system goes to work finding every identifiable part and building an inverse copy of. This is the “Immunogenic Load”.  It sees a turret, banquet room, gargoyle, bridge, roof gable, and the body stockpiles antibodies matching the castle parts.  Next time, if your system’s inverse copy matches, this castle won’t be so lucky. The alert goes out quickly, and the immune system goes into high gear attaching antibodies and smashing the castle, often before you even feel sick again.  Early vaccines smashed the castle, then presented the bits in the vaccine. Same process, the body identifies TONS of unique parts that can put up the “most wanted” sign in the immune system base, and stockpiles these antibodies. Nowadays, vaccines present ONE unique part that every Hogwarts has.  A turret, pehaps.  The end result is that even with so many different diseases protected, the actual work and stockpiling the body does is significantly less than even one early vaccine.

The Drug Companies and Doctors are in Cahoots, How Do I Believe Medical Science?  This one is tough.  First, full disclosure.  I have turned down every opportunity to be paid to represent a drug company:  No “speaker boards”, no writing a sponsored study paper, nada.  I have advised various companies for free about needle pain, but on my own nickel, or in two instances for an admittedly swanky dinner.  I like food. Unquestionably I ate a lot of meals in med school sponsored by different drugs, and until the Pharma 2009 laws cut off giveaways, I had gotten lots of plastic pens (most broke quickly, but some definitely looked cool for a while.  Some blinked!!).  A recent study said medical students who were fed were later more likely to prescribe newer, more expensive drugs, so I’m definitely in the tainted group.  With that disclosure, as a researcher, this is how I perceive the system working.

When a university researcher gets a grant to do a study, the UNIVERSITY gets the bucks, not the researcher.  No reason not to keep results honest, and if the volunteer reviewers of the journal think the researcher’s work was biased or shoddy, that will affect the career of the researcher FAR more than any imagined pressure from the university to “keep getting those drug bucks”.  I have friends who were pressured to report this table or that one rather than the one they felt was most honest.  My friends bowed out of authorship, but clearly this slanting does happen, though there are new stricter rules about publishing industry funded studies.  For the most part, though, the coin of the realm for university street cred is FEDERAL funding, not drug company.  Most of the studies of disease conducted are done by the government anyway, and no matter how much of a conspiracy or incompetency theorist you are, the government really would rather save money.  Kids with severe autism cost the health system enormously.  Deaths and hospitalizations from measles, pertussis, varicella -> shingles also cost the health system, so people in oversight have a very vested interest in NOT wasting taxpayer money reimbursing vaccinations if they don’t work or lead to costly side effects.  HOWEVER- the drug companies get to present their cost-benefit analysis for committee vetting.  To my knowledge, no one is looking at the future costs of needle fears and healthcare avoidance and factoring them into the equation.  I know a study showed that keeping track of all the new vaccines and explaining them to parents has added a 0.75 Full Time Equivalent of work to a medium sized pediatric practice, unreimbursed.  To my knowledge, these costs aren’t considered when adding a new vaccine is weighed.

Sometimes, though, there are unexpected savings.  Absolutely, I admit many many fewer kids with horrible pneumonia since the pneumococcal vaccine, but I also see many fewer raging ear infections and complications from ear infections.  This is a monetary win, not to mention the win in pain and late night screaming suffering.  Pain prevention is my first love, and we went through 5 sets of tubes in 3 kids, so this reduction in ear infections matters to me as a mom.

Religious/legal exemption:  I hear the argument from time to time of vaccine refusal on religious grounds.  While I suspect that this religion is “I don’t feel comfortable-itis-ism”, it’s helpful to know the actual grounds on which these claims are based, and the legal landscape concerning parents’ extent of rights on their children’s health.  (Some of this is a distillation of a lecture by Paul Offitt MD at the 2012 Pediatric National Conference and Exhibition.)

The scriptures on which religious exemptions are based were written well before even the concept of vaccination.  The Old testament was written between 1400-400 BC, the New Testament 117-138 AD;, and the Qur-an 610AD.  How, then, are the presumptive prohibitions extrapolated?

Even when a religion extrapolates a prohibition into a refusal, there is a legal support for protecting children with immunizations.  A 1944 Supreme court ruling evaluated whether being a Jehovah's witness allowed parents to force young children to distribute pamphlets for long hours or in uncomfortable situations.  "Parents may be free to become martyrs themselves; but it does not follow they are free...to make martyrs of their children." 

Constitutionally, do US citizens have a right to exempt themselves from vaccines?  Historically, the precedent is “nope”.  In the case of Jacobson v. Massachusetts (1905), an outbreak of smallpox in Boston prompted the Cambridge board of health to require getting a smallpox vaccine or suffering a then-hefty $5 fine.  Henning Jacobson refused both, sued, and lost.  To encapsulate the ruling, ‘The liberty secured by the Constitution of the United States does not import a right to be wholly freed."  Along the same lines, in 1922 Rosalyn Zucht was expelled from Brackenridge High School in San Antonio for refusing the smallpox vaccine in the absence of an outbreak.  She lost too, as the US supreme court unanimously supported vaccination.

Until cases are taken to the Supreme Court, however, states rights trump, which is why there is such a patchwork of laws across the US.  In New York, Christian Scientists lobbied to be exempt from vaccination.  Cases including DeWitt High School (1965), Austin (1968) and others secured the right of Christian Scientists to refuse polio vaccine.  Subsequently, a1972 polio outbreak in Daycroft left 17 of 168 affected paralyzed.

A similar permissive law in Pennsylvania allowed religious exemptions, which led to a 1991 measles outbreak in Philadelphia.  Churchgoers in the First Century Gospel and Faith tabernacle were often unvaccinated, and were the hardest hit.  Of 486 cases, there were 6 deaths.  The outbreak spread to the community, and there were 3 deaths of the 938 who contracted the disease.

Often the argument cited legally is that the 1st amendment states that Congress shall make no law “respecting an establishment of religion, or prohibiting the free exercise thereof."  In two instances, however, laws have been passed for the protection of children: Mormons can't practice polygamy, and Jehovah's Witnesses are not allowed to deny their children blood transfusions.  Because of the 14^th amendment, which says that “No state shall deprive any person of life liberty or property without due process under the law, or withhold without due process", one can argue that withholding vaccines from children is done without due process.  In fact, the case of Brown v. Stone concluded that vaccinations are equal protections, but again, state laws can trump federal until their particulars are argued.

Other Resources:

CDC.gov/vaccines -

Immunizationinfo.org

Immunize.org

Vaccinateyourbaby.org

ECBT.org

vaccine.chop.edu The Children's Hospital of Philadelphia Vaccine education center.  Some cool history.

Vaccinesafety.edu Independent evaluations of vaccine safety, and links to laws and legislation

pkids.org - Parents of Kids with Infectious Diseases.  This site has good descriptions of how vaccines and the immune system work.  What the world would look like without vaccines.  Q&A about vaccine safety