Journal Club Debunks Anti-Vaccine Myths

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American Family Physician, the journal of the American Academy of Family Physicians, has a feature called AFP Journal Club, where physicians analyze a journal article that either involves a hot topic affecting family physicians or busts a commonly held medical myth. In the September 15, 2010 issue they discussed “Vaccines and autism: a tale of shifting hypotheses,” by Gerber and Offit, published in Clinical Infectious Diseasesin 2009.

The article presented convincing evidence to debunk 3 myths:

1. MMR causes autism.
2. Thimerosal (mercury) causes autism.
3. Simultaneous administration of multiple vaccines overwhelms and weakens the immune system, triggering autism in a susceptible host.

Gerber and Offit reviewed 13 large-scale studies that demonstrated no association between the MMR vaccine and autism. These included ecologic studies, retrospective observational studies and prospective observational studies.  The findings were consistent; the only outlier in all the studies of MMR was Dr. Andrew Wakefield’s small, discredited 1998 study, which was fully retracted by The Lancet in early 2010.

They reviewed 7 large-scale studies (again, ecologic, retrospective, and prospective) that consistently demonstrated no association between thimerosal and autism. They showed that the hypothesis was not biologically plausible, since the symptoms of mercury poisoning are distinct from those of autism and are not produced by the thimerosal in vaccines.

They showed that the overload hypothesis is not credible because

1. The immunologic load has dropped from 3000 components in the 7 vaccines used in 1980 to less than 200 in the 14 vaccines recommended today.
2. An infant’s immune system is capable of handling the thousands of antigens it is exposed to early in life.
3. Vaccinated children are not more susceptible to infections.
4. Autism is not an autoimmune disease.

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Vaccine Misconception of the day – Aluminum in vaccines

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One of the common arguments the anti-vaccine advocates use is the “toxins in vaccines” argument. They say that because some substance in vaccines is known to be toxic, such as aluminum, then its mere presence makes vaccines dangerous. What they fail to mention in almost every case however is how much of said substance is in vaccines, and at what levels is this substance toxic.

Water can be toxic to a human in high enough quantities; it’s called drowning. Oxygen can be poisonous; it’s called oxygen poisoning. The list of examples goes on and on but the take home point is this: any substance can be toxic in the right dose; and most substances will not be toxic at low enough levels. As they say the dose makes the poison. The same applies to aluminum.

So, how much aluminum is there in vaccines anyway, and is that level dangerous for babies? To answer that, the Vaccine Education Center at the Children’s Hospital of Philadelphia has set up a short, concise, informative PDF that is available to all, for free, titled “Aluminum in Vaccines: What you should know“. And unlike those in the anti-vaccine camp, the Vaccine Education Center provides all their sources in the PDF itself, for anyone who wants to verify the accuracy of their report.

What they report should satisfy everyone’s curiosity.

During the first 6 months of life, infants could receive about 4 milligrams of aluminum from vaccines. That’s not very much: a milligram is one-thousandth of a gram and a gram is the weight of one-fifth of a teaspoon of water. During the same period, babies will also receive about 10 milligrams of aluminum in breast milk, about 40 milligrams in infant formula, or about 120 milligrams in soy-based formula.

So to put this in perspective: a baby will get 2.5 times the amount of aluminum from breast milk, 10 times the aluminum from infant formula, and 30 times the aluminum from soy-based formula. I know of no babies that are raised without either breast milk or formula, including the babies of each person in the anti-vaccine camp, and any baby who wasn’t vaccinated due to parent’s fear of aluminum toxicity in vaccines.

It appears to me that the anti-vaccine crowd should switch its focus from “greening” vaccines to “greening” baby formula. I hear Big Formula makes a lot of money too out of its product….!

If “mommy knows best” than Jenny McCarthy is wrong

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Not that this will settle anything, because science fact is not decided by arguments from popularity, but I think it is important to point this out. Many in the anti-vaccine community appeal to a “mommy knows best” argument, in which they will tell a very emotional story about how a mother saw their child fade away right after getting a vaccine. McCarthy herself has told her son’s story many times, telling us how she, to paraphrase, saw his soul fade away right after the vaccine. The implication is that mothers of autistic children know that their children’s autism is caused by vaccines.

Nevertheless, surveys do not support this notion. A survey of 62 families of autistic children found out that only 29% of parents of autistic children blame vaccines for their children’s autism (page 6). So if mothers know best, it appears McCarthy is in the minority within the community of parents of autistic children. It appears, at least from this survey, that about 70% of parents of autistic children do not blame vaccines for their children’s autism. So if the results of this survey hold, and can be extrapolated out to the entire population of parents of autistic children, which is quite a stretch to be honest, it would appear that for every mommy instinct blaming vaccines, there are two mommy instinct not blaming vaccines.

So what does this mean for the vaccines-autism “controversy”. Absolutely nothing; the correlation, or lack there of, between vaccines and autism is a scientific issue, not a popularity contest. The fact is what it is, regardless of what parents think, and I’m willing to say that even when parental opinion is on my side. Is Jenny McCarthy, and all the rest in the anti-vaccine community, willing to do the same? The answer to that question would shed so much light on their ability, and willingness, to find out the truth.

How are new vaccines tested before public use?

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It is reasonable to ask how new vaccines are tested  before they are cleared for public use. The National Institute of Allergy and Infectious Diseases explains the various studies that must be done before the new vaccine is approved by the FDA. There are various stages of testing a vaccine must undergo before it is cleared for use. They are as follows.

1) Animal Testing - Firstly, the new vaccine is tested in animals for safety and immunogenicity, meaning that is must be safe and induce enough of an immune response to justify moving on with human trials.

2) Phase I Study – After a promising animal test, the process moves to what is referred to as clinical trials, meaning testing in human subjects. The first step in this process is a Phase I study, which is the first setting in which an experimental vaccine is given to people. The trial, which can last up to 2 years, may enroll between 20 to 100 volunteers. A Phase I study primarily seeks information on safety, particularly looking for any vaccine-related side effects. The study can also provide data on the dose and administration schedule needed to achieve the optimal immune responses.

3) Phase II Study – Once Phase I studies show the experimental vaccine is safe, well tolerated, and appears promising, it can advance into Phase II. These studies, which can last longer than 2 years, enroll between 100 to 300 volunteers. In these studies researchers gather more data on safety and immunogenicity. These studies also test the effects of varying the doses, and are also referred to as dose-ranging studies.

4) Phase III Study - The most promising vaccine candidates move into Phase III, enrolling 10,000 or more people. A Phase III study, which can last up to 4 years, is typically designed to ensure enough data are collected on safety and effectiveness to support a license application to FDA.

An intermediary study, called a Phase IIb study is being considered, as a middle step between the Phase II and the Phase III studies. This study would enroll between 2,000 and 9,000 volunteers. It appears, as of the time of writing, that Phase IIb studies are not a requirement like the others.

Besides the required tests, the FDA may require additional testing and data at any point. Furthermore, the proposed manufacturing facility undergoes a pre-approval inspection during which production of the vaccine as it is in progress is examined in detail. Vaccine approval also requires the provision of adequate product labeling to allow health care providers to understand the vaccine’s proper use, including its potential benefits and risks, to communicate with patients and parents, and to safely deliver the vaccine to the public.

Until a vaccine is given to the general population, all potential adverse events cannot be anticipated. Thus, many vaccines undergo Phase 4 studies-formal studies on a vaccine once it is on the market. Also, the government relies on the Vaccine Adverse Event Reporting System (VAERS) to identify problems after marketing begins. The VAERS system and how it works is discussed further on this website.

Safety of influenza vaccine during pregnancy

Today we will look at the recent recommendation by the CDC, the American College of Obstetricians and Gynecologists,  that, all people over 6 months of age, including pregnant women receive the flu vaccine. Anti-vaccination groups have already come out,  insinuating that the safety of the flu vaccine given during a woman’s pregnancy has not been established. Is that true? Are there any studies that have looked at the safety of the influenza vaccine for pregnant women? The answer is yes, at the very least there is one that I was able to find, using simply Google.

Safety of influenza vaccination during pregnancy.

Munoz FM, Greisinger AJ, Wehmanen OA, Mouzoon ME, Hoyle JC, Smith FA, Glezen WP.

Study Summary – The objective of the study was to “evaluate the safety of influenza vaccine that is administered in the second or third trimester of gestation”. A retrospective electronic database search of 5 influenza seasons (July 1, 1998, to June 30, 2003) was performed at a large multispecialty clinic in Houston, Texas. Immunization rates were calculated, and outcomes of pregnancy were compared between healthy women who received influenza vaccine, and a control group of healthy unvaccinated women who were matched by age, month of delivery, and type of medical insurance.

Results - Among 7183 eligible mother-infant pairs, only 252 pregnant women (3.5%) received the influenza vaccine. The mean gestational age at the time of influenza vaccination was 26.1 weeks (range, 14-39 weeks). No serious adverse events occurred within 42 days of vaccination, and there was no difference between the groups in the outcomes of pregnancy (including cesarean delivery and premature delivery) and infant medical conditions from birth to 6 months of age.

Conclusion – This study provides good evidence that pregnant women who receive the flu vaccine during the last 2 trimesters of the pregnancy, and their babies at least up to 6 months of age, face no more risks or complications than pregnant women who do not receive the flu shot during the last 2 trimesters of their pregnancy, and their babies up to 6 months of age. It appears the claims of the anti-vaccination crowd are rejected, at least as far as this study is concerned.  The authors concluded as such:

Influenza vaccine that was administered in the second or third trimester of gestation was safe in this study population.

Vaccines don’t raise arthritis risk in adults

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Common vaccinations don’t raise risk of rheumatoid arthritis, easing fears that they’re linked to the inflammatory disease, according to a new study.

Case reports have suggested vaccines, possibly because of their immune-activating adjuvants, could trigger rheumatoid arthritis, a painful autoimmune disease caused by the body’s natural defenses attacking and inflaming joints.

But a study published online Tuesday in the Annals of the Rheumatic Diseases found no link between common vaccinations for flu, hepatitis, diphtheria and other illnesses and an increased risk for rheumatoid arthritis. The study also found no increased risk for patients getting vaccinations who had a genetic susceptibility to the disease, or who were smokers. Smoking has long been thought to be a major risk factor for the disease.

Receiving multiple vaccines also didn’t up the chances of getting afflicted by the joint disease.

“Our results indicate that immunological provocation of adults with common vaccines in their present form is not a major risk factor for RA,” write the authors, led by Camilla Bengtsson, a researcher at the Karolinska Institute in Stockholm, Sweden. “In addition, our results indicate that active immunization does not increase the risk of RA in individuals with established risk factors.”

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inFact: Vaccine Ingredients

Study links combination MMRV vaccine with double the risk for febrile seizures

The MMRV vaccine is a combination vaccine, which combines the MMR vaccine and the Varicella vaccine in a single dose. The MMR vaccine itself is a combination vaccine, providing protection from Measles, Mumps and Rubella. A recent study, published in the journal Pediatrics, shows that the risk for febrile seizures, in the 7-10 day period following receipt of the MMRV vaccine, is twice as big as compared to receiving separate MMR & Varicella vaccines in the same day, for children 12-23 months of age.

Measles-Mumps-Rubella-Varicella Combination Vaccine and the Risk of Febrile Seizures

Nicola P. Klein, Bruce Fireman, W. Katherine Yih, Edwin Lewis, Martin Kulldorff, Paula Ray, Roger Baxter, Simon Hambidge, James Nordin, Allison Naleway, Edward A. Belongia, Tracy Lieu, James Baggs, and Eric Weintraub for the Vaccine Safety Datalink 2010;126;e1-e8; originally published online Jun 29, 2010; Pediatrics DOI: 10.1542/peds.2010-0665

Study Summary – The researchers used 2000–2008 Vaccine Safety Datalink data to compare seizures and fever visits, restricted to emergency room or hospital visits,  among children aged 12 to 23 months, during the 42 days after receipt of the MMRV vaccine, or the separate MMR +
varicella vaccines. The study population included 83, 107 children vaccinated with MMRV between January 2006 and October 2008 and 376, 354 vaccinated with MMR
varicella between January 2000 and October 2008.  The secondary comparison groups consisted of 145, 302 children who received MMR vaccine alone and 107, 744 who received varicella vaccine alone from 2000 to 2008. The authors monitored weekly seizure visits and compared the rates between the vaccines.

Results - After vaccination with all measles-containing vaccines, seizure incidence peaked during days 7 to 10; the most prominent peak was recorded after MMRV vaccination. During days 7 to 10, unadjusted rates for seizures were 84.6 seizures per 1000 person-years after MMRV vaccination, 42.2 seizures per 1000 person-years after MMR
+ varicella vaccination, and 26.4 seizures per 1000 person-years after MMR vaccination alone. Unadjusted rates during days 7 to 10 were nearly 8 times higher for MMRV and 4 and 3.5 times higher for MMR
varicella and MMR vaccination alone, as compared to Varicella vaccine alone.

Conclusion – The study looked at over 459 000 children, 12-to-23 months of age, who were vaccinated with either the MMRV vaccine, or separate MMR & Varicella vaccines, and found the MMRV to be associated with increased fever and seizures 7-10 days following vaccination. When compared to separate MMR + Varicella vaccine received at the same time, the combination MMRV vaccine was associated with a two-fold increase in risk of having a febrile seizure in the 7-10 days following vaccination. The authors estimated this meant 1 additional case of febrile seizure for every 2,300 doses of MMRV vaccine given, as compared to separate MMR & Varicella vaccines received at the same time. There was no difference in seizure risk outside of the 7-10 day window. The study shows that both MMRV, and MMR+Varicella vaccines are associated with increased seizure risk in the 7-10 day window, as compared to Varicella vaccine alone, with the risk from MMRV being twice as high as the separate MMR+Varicella vaccinations. Here is what the authors of the study had to say:

Among 12- to 23-month-olds receiving their first dose of measles-containing vaccine, the risk of fever and seizure are elevated 7 to 10 days after vaccination. The use of MMRV vaccine instead of separate MMR
varicella vaccines approximately doubles the risk for fever and febrile seizures, resulting in 1 additional febrile seizure for every 2300 doses of MMRV vaccine administered instead of separate MMR and varicella vaccines.

Bottom Line:  Talk to your pediatrician about this; it appears the best route is to take the separate MMR+Varicella vaccines as opposed to the single MMRV shot. Febrile seizures are fairly common, with 1 in 25 children experiencing at least one seizure. While witnessing a child going through one is scary, they are generally harmless. According to the National Institute of Neurological Disorders and Stroke:

Although they can be frightening to parents, the vast majority of febrile seizures are harmless. During a seizure, there is a small chance that the child may be injured by falling or may choke from food or saliva in the mouth. Using proper first aid for seizures can help avoid these hazards (see section entitled “What should be done for a child having a febrile seizure?”).

There is no evidence that febrile seizures cause brain damage. Large studies have found that children with febrile seizures have normal school achievement and perform as well on intellectual tests as their siblings who don’t have seizures. Even in the rare instances of very prolonged seizures (more than 1 hour), most children recover completely.

Between 95 and 98 percent of children who have experienced febrile seizures do not go on to develop epilepsy. However, although the absolute risk remains very small, certain children who have febrile seizures face an increased risk of developing epilepsy. These children include those who have febrile seizures that are lengthy, that affect only part of the body, or that recur within 24 hours, and children with cerebral palsy, delayed development, or other neurological abnormalities. Among children who don’t have any of these risk factors, only one in 100 develops epilepsy after a febrile seizure.

Mercury in vaccines not linked to autism, new study finds

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NEW YORK — A new government study adds to the evidence that thimerosal, a mercury-based preservative until recently found in many vaccines, does not increase children’s risk of autism.

It shows kids who had been exposed as babies to high levels of the preservative — through vaccines they received or their mothers received while pregnant — were no more likely to develop autism, including two distinct subtypes of the condition.

“This study should reassure parents about following the recommended immunization schedule,” said Dr. Frank Destefano, director of the Immunization Safety Office at the Centers for Disease Control and Prevention (CDC) in Atlanta, and the study’s senior author.

Concerns about a link between vaccines and autism were first raised more than a decade ago by British physician Andrew Wakefield.

His report, based on 12 children, has since been discredited and was retracted earlier this year by the journal that published it. In the meantime, it sparked a fierce worldwide debate among scientists and a health scare that caused many parents to shy away from recommended vaccines like the one against measles, mumps and rubella.

Outbreaks of all three diseases followed.

One widespread worry has been that thimerosal might play a role in the development of autism, a condition that affects as many as one in 110 U.S. children, according to the CDC.

Most scientists consider autism a developmental disorder, likely influenced by genes.

Autism spectrum disorders range from mild Asperger’s Syndrome to severe mental retardation and social disability, and there is no cure or good treatment.

The CDC researchers used data for U.S. children born between 1994 and 1999, who were enrolled in one of three managed care organizations.

They found 256 children with an autism spectrum disorder and compared them with 752 children who did not have the condition, but were matched for age and sex.

No matter when a child had been exposed to thimerosal — before birth when the mother had a shot, or when the child itself was vaccinated as a baby or toddler — there was no increase in the risk of any type of autism spectrum disorder.

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No link between vaccines and autism, appeals court rules

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WASHINGTON — A federal appeals court on Friday upheld a ruling that vaccines are not to blame for autism.

The U.S. Court of Appeals for the Federal Circuit upheld a decision last year by a special vaccine court, which concluded there’s little if any evidence to support claims of a vaccine-autism link.

Scientist years ago reached that conclusion, but more than 5,500 families sought compensation through the government’s Vaccine Injury Compensation Program.

Friday’s ruling came in the case of Michelle Cedillo of Yuma, Ariz., who is disabled with autism, inflammatory bowel disease and other disorders that her parents blame on a measles vaccine given at 15 months.

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