Ever since there has been widespread use of vaccination for disease prevention there has been an anti-vaccine movement. Recently, their efforts have focused on the alleged link between vaccines and autism – I have written extensively about the evidence against such a link on Science-Based Medicine and NeuroLogica. But the anti-vaccine movement goes beyond the autism question.
One measure of the success of a misinformation campaign is how embedded the misinformation has become in the culture. For me a quick measure of this penetration are discussions on the SGU forums – SGU listeners tend to be well-informed, generally skeptical, and have some interest in science. If misinformation is represented in this group it is probably widespread.
A recent thread on vaccines shows that often vague but sometimes specific fears about vaccines are indeed likely to be widespread. It is always heartening to see our listeners do a great job, either through honed skeptical skills or specific knowledge, of countering much of these fears. But I will review some of the questions raised.
Vaccines are one of the safest and most effective public health measures ever devised. The safety of vaccines are carefully tested prior to incorporation into the vaccine schedule. Vaccines are then monitored after use. There is a Vaccine Adverse Event Reporting System (VAERS) that the CDC uses to track the safety of vaccines. Vaccine safety is also assessed by professional organization, like the American Academy of Pediatrics. There are many academic physicians who are interested in vaccines as part of their academic career, and they independently research the effects and safety of vaccines.
No one has ever suggested that vaccines are without risk – individuals may have adverse reactions to vaccines. But the benefits far outweigh the risks – even to the individual. Far from trying to cover this up, the CDC is actively trying to gather as much information as they can through VAERS. They write:
These coincidences make it difficult to know whether a particular adverse event resulted from a concurrent condition or from a vaccination. Therefore, doctors and other vaccine providers are encouraged to report all adverse events following vaccinations, whether or not they believe that the vaccination was the cause.
The approach is to gather information on all adverse events and then try to sort out statistically which are likely to be genuinely caused by vaccines. In the United States, there is also a compensation system for those injured.
The CDC maintains a list of reported side effects for each vaccine here.
Too Many Too Soon
There is power in a pithy slogan – damn those anti-vaccinationists. Even if there is absolutely no science behind it, such a phrase can resonate, or at least leave people with vague questions and uncertainty. Are we giving our children, with their delicate immune systems, too many vaccines? Are we depriving them of the necessary experience of fighting off infections naturally, thereby inadvertantly weakening their immune systems? The evidence says no.
The current recommended US schedule includes about 31 injections (depending on how many flu shots are given) between birth and six years of age. Many of these are given at the same time to minimize office visits. A couple of the injections, like MMR and DTaP, are combinations. There are 15 different infectious organisms that are vaccinated against, but most require a series of injections to develop full immunity.
It is natural for parents to have an overwhelming protective instinct for their children, and it is upsetting to see your child fearful and crying because they had to get their shots – especially when they are healthy (as opposed to being treated for an acute illness). I can understand the visceral reaction – what are you doing to my child? What are you putting into their tiny helpless bodies? I have two children – I get it. But our children are best served by decisions that are evidence-based and rational, not visceral and emotional.
The evidence shows that even infant immune systems can handle vaccines and generally respond only by making the desired antibodies to the organisms against which they are being vaccinated.
Anti-vaccinationists claim that their young immune systems are being overwhelmed by the schedule of vaccines – but there is no evidence for this. Further, the infant and young child immune system is bombarded with thousands of antigen challenges. The additional challenge from vaccines is a minor addition. Further still – while the number of vaccines has increased, the efficiency of these vaccines has also increased. Modern vaccines present fewer (but more targeted) antigens to the immune system than older vaccines – so even though the vaccine schedule has increased, children today are getting less of an immune challenge than in the past.
Therefore – there is absolutely no empirical or even theoretical basis to the “too many too soon” slogan.
On the other hand – there is a risk of delaying vaccination. The schedule was devised in order to protect children from diseases before they are likely to get them. Any delay in the schedule leaves children vulnerable for longer – statistically it will increase infections. Withholding an intervention is a decision with risks also.
The Risk of Overuse
Some have raised the concern that vaccines are being overused, and thereby are weakening immune systems. This has been likened to the overuse of antibiotics. But there is absolutely no analogy here.
Antibiotic overuse allows bacteria to evolve resistance to antibiotics. Antibiotics do not weaken the immune system of the individual, they just speed up the evolutionary war between modern science and infectious bacteria. Proper use of antibiotics is necessary to minimize the development of resistance.
Vaccines do not cause resistance. They stimulate the immune system (not weaken it – an absurd claim) by presenting specific proteins or antigens to the immune system, which will then mount a mini-immune reaction against them and create memory B-cells. These B-cells are primed to mount vigorous reaction the next time they encounter the same antigen. This way an infecting organism can be wiped out by the immune system even before a clinical infection can take place.
Some anti-vaccinationists have argued that natural infections create more immunity than vaccines. There is no evidence for this. Some immunity does fade over time, from either vaccines or infection, but this can be handled with booster injections. Further, it is not worth the risk of suffering a serious infection just so that those who survive will have stronger immunity – even if this were true.
Herd Immunity – or Who Needs Vaccines Anyway
The vaccination program is best understood as a strategy for public health – not just individual health. The two are, of course, closely related, but strategically vaccines work best on populations. The reason for this is herd immunity. Once a population has >90% or so immunity to a disease, then it cannot spread effectively. This helps protect those for whom the vaccines did not work, for whatever reason (they are not 100% effective) and those who cannot be vaccinated because of some other illness or health condition.
This has led some parents to think that the benefits of vaccination for their individual child is not worth the risk of vaccines. This belief is further created by the fact that most parents today have not had any experience with the serious childhood infections of the past. Who today has seen polio, or even a severe case of whooping cough. Vaccines, to some degree, are victims of their own success.
The data show that individual benefits do outweigh individual risks. No one is asking individual children to take a hit for the team. But on top of the individual benefit there is also a societal benefit – herd immunity – that in turn does also benefit all members of society. The two cannot really be separated.
Also, if enough individuals decide not to vaccinate, then herd immunity breaks down and everyone is then at higher risk for resurgent infections. We are already seeing this in various communities with measles. Everyone is then at higher risk – but especially those who do not vaccinate.
There is also the issue of eradication. For those organisms that do not have any animal host other than humans, we can completely eradicate the disease through vaccination. We have already done this with small pox. We are on the brink of doing this with polio – this success being stalled by fearmongering in Nigeria about vaccines from the West being spiked with HIV and anti-fertility drugs.
Some have argued that we are vaccinating against disease that are relatively benign – like chicken pox. But again, this is based upon misinformation. Chickenpox can be very serious, and historically has resulted in about 50 deaths per year and hundreds of hospitalizations in children. Infected children also pose a risk to adults, for whom the infection is even worse. And once infected with chicken pox, the virus survives forever in the dorsal root ganglion – nerve cells in the spinal cord. They can be reactivated causing shingles. While it is more likely for shingles to occur under stress or immune compromise, they occur at random, even in a perfectly healthy individual. Shingles can cause an extremely painful and difficult to treat chronic pain syndrome. Personally, I would rather have been vaccinated against chicken pox as a child than have the risk of developing shingles.
Vaccines are safe and effective. There are multiple layers in place to monitor vaccine safety. Academic physicians and researchers spend a great deal of time and effort thinking about vaccines and conducting research on them. It is naive to think that basic flaws in the theory or execution of vaccines has escaped academic notice.
Gross misinformation about vaccines has now permeated the public, primarily through the internet, largely originating from dedicated groups of people who are ideologically anti-vaccine. This does not mean that vaccines are beyond question, that we do not need to continue to research and improve vaccines, as well as carefully monitor their safety. Of course we do – and we are. No one is promising that they are risk free.
But given that there are groups dedicated to spreading misinformation, everyone needs to be skeptical of any information they hear about vaccines. Don’t believe anything on hearsay. Check sources carefully, and look for counterbalancing information and opinions before accepting any claims. This includes pro and con – including this blog entry.
As with any scientific topic – reliability and authority rests with the transparent and carefully considered consensus of scientific opinion, not with any individual.