JPeds: Autism NOT Linked To Timing & Number Of Childhood Vaccines

 

 

# 7040

 

Despite a lack of any credible scientific evidence to support the notion, many parents believe that the number and timing of recommended childhood vaccinations increase the risk of their child developing autism.

 

This has become a hot button issue, and a centerpiece of the anti-vaccine movement’s rhetoric.

 

While unlikely to appease hardcore anti-vaccine activists, hopefully most parents will be reassured by the following CDC study that appeared overnight in the Journal of Pediatrics. 

 

Researchers found no relationship between the number, or timing, of childhood vaccines and the development of autism spectrum disorder.

 

First stop, a press release/editorial, followed by links to the study in the Journal Pediatrics, and an NPR blog.

 

 

The risk of autism is not increased by 'too many vaccines too soon'

Cincinnati, OH, March 29, 2013 -- Although scientific evidence suggests that vaccines do not cause autism, approximately one-third of parents continue to express concern that they do; nearly 1 in 10 parents refuse or delay vaccinations because they believe it is safer than following the Centers for Disease Control and Prevention's (CDC) schedule.

 

A primary concern is the number of vaccines administered, both on a single day and cumulatively over the first 2 years of life. In a new study scheduled for publication in The Journal of Pediatrics, researchers concluded that there is no association between receiving "too many vaccines too soon" and autism.

 

Dr. Frank DeStefano and colleagues from the CDC and Abt Associates, Inc. analyzed data from 256 children with autism spectrum disorder (ASD) and 752 children without ASD (born from 1994-1999) from 3 managed care organizations. They looked at each child's cumulative exposure to antigens, the substances in vaccines that cause the body's immune system to produce antibodies to fight disease, and the maximum number of antigens each child received in a single day of vaccination.

 

The researchers determined the total antigen numbers by adding the number of different antigens in all vaccines each child received in one day, as well as all vaccines each child received up to 2 years of age. The authors found that the total antigens from vaccines received by age 2 years, or the maximum number received on a single day, was the same between children with and without ASD. Furthermore, when comparing antigen numbers, no relationship was found when they evaluated the sub-categories of autistic disorder and ASD with regression.

 

Although the current routine childhood vaccine schedule contains more vaccines than the schedule in the late 1990s, the maximum number of antigens that a child could be exposed to by 2 years of age in 2013 is 315, compared with several thousand in the late 1990s. Because different types of vaccines contain varying amounts of antigens, this research acknowledged that merely counting the number of vaccines received does not adequately account for how different vaccines and vaccine combinations stimulate the immune system. For example, the older whole cell pertussis vaccine causes the production of about 3000 different antibodies, whereas the newer acellular pertussis vaccine causes the production of 6 or fewer different antibodies.

 

An infant's immune system is capable of responding to a large amount of immunologic stimuli and, from time of birth, infants are exposed to hundreds of viruses and countless antigens outside of vaccination. According to the authors, "The possibility that immunological stimulation from vaccines during the first 1 or 2 years of life could be related to the development of ASD is not well-supported by what is known about the neurobiology of ASDs." In 2004, a comprehensive review by the Institute of Medicine concluded that there is not a causal relationship between certain vaccine types and autism, and this study supports that conclusion.

The study may be accessed in PDF form at:

 

"Increasing exposure to antibody-stimulating proteins and polysaccharides in vaccines is not associated with risk of autism,"

by Frank DeStefano, MD, MPH, Cristofer S. Price, ScM, and Eric S. Weintraub, MPH, appears in The Journal of Pediatrics (www.jpeds.com), DOI 10.1016/j.jpeds.2013.02.001, published by Elsevier.

 

For more on all this, NPR’s Shots blog has the following report and audio story.

 

Number Of Early Childhood Vaccines Not Linked To Autism

by Jon Hamilton

March 29, 2013 3:08 AM

Listen to the Story

Of Pregnancy, Flu & Autism

 

Photo Credit – CDC

 

# 6711

 

We’ve known for a long time that influenza during pregnancy can endanger the mother, and unborn child’s life. Furthermore, it appears that pregnant women are more susceptible to influenza than are non-pregnant women.

 

Why is not exactly known, although it is theorized that the normal protections of a woman's immune system are temporarily altered to allow her to carry what is essentially a foreign body - a fetus - without rejection.

 

During the 2009 H1N1 pandemic pregnant women were six times more likely to be hospitalized than non-pregnant women (see Pregnancy & Flu: A Bad Combination). 

 

And in 2011, in BMJ: Perinatal Outcomes After Maternal 2009/H1N1 Infection we saw a study where pregnant women who were admitted to the hospital with an  H1N1 infection experienced a 3 to 4 times higher rate of preterm birth, 4 to 5 times greater risk of stillbirth, and a 4 to 6 times higher rate of neonatal death.

 

Over the past decade we’ve also seen a handful of studies tentatively linking prenatal exposure to influenza (or an influenza-like-illness) with a variety of child and adolescent development disorders. 

 

A few examples include:

 

• In a 2004 study (Serologic evidence of prenatal influenza in the etiology of schizophrenia  Brown et al.) found a 7-fold increase in the risk of developing schizophrenia when exposed to influenza during the first trimester. No increased risk was found for exposure during the second and third trimester.

 

• Another study from 2008 (Structural brain alterations in schizophrenia following fetal exposure to the inflammatory cytokine interleukin-8  Ellman et al.) suggested that it was prenatal exposure to a type of protein - (proinflammatory cytokines, specifically interleukin-8) – produced by the body during viral infections, that can lead (in rare cases) to brain abnormalities.

 

• And earlier this year, research by a team at UC Davis found that fever (from any cause) during pregnancy more than doubled the odds of having a child with autism or developmental delays (see  Is Maternal Influenza or Fever During Pregnancy Associated with Autism or Developmental Delays? Results from the CHARGE (CHildhood Autism Risks from Genetics and Environment) Study  Zerbo et al.)
• • Flu, specifically, during pregnancy was not associated with greater developmental risks only fever by `any cause’.
  • Children of mothers who took antipyretics for fever did not show any increase in developmental disorders.

 

These studies are admittedly small and less than conclusive.

 

And while they suggest an increase in relative risk over pregnancies without fever or viral infection – in terms of absolute risk – the odds that a mother’s fever or viral infection during pregnancy would result in a developmentally challenged child remains low.

 

Today, we’ve a new study appearing in the journal Pediatrics that adds, incrementally, to earlier suspicions regarding prenatal exposure to influenza and the risks of developmental disorders.

 

Researchers followed up on more than 96,000 Danish children born between 1997 and 2003. They compiled a (self reported) history of the mother’s pregnancy (including infections, fevers, and antibiotic use), and compared that to diagnoses of ASD and infantile autism among the children.

 

Autism After Infection, Febrile Episodes, and Antibiotic Use During Pregnancy: An Exploratory Study

Hjördis Ósk Atladóttir, MD, PhD, Tine Brink Henriksen, MD, PhD, Diana E. Schendel, PhD, and Erik T. Parner, PhD^d

RESULTS: Overall, we found little evidence that various types of mild common infectious diseases or febrile episodes during pregnancy were associated with ASD/infantile autism. However, our data suggest that maternal influenza infection was associated with a twofold increased risk of infantile autism, prolonged episodes of fever caused a threefold increased risk of infantile autism, and use of various antibiotics during pregnancy were potential risk factors for ASD/infantile autism.

 

The two major findings were:

 

• A twofold increase in autism among children with prenatal influenza exposure
• A threefold increase in autism among children with prolonged prenatal fever exposure

 

It should be noted that these are relative risk increases, and once again, the absolute risk of having an autistic or developmentally challenged child after experiencing an influenza infection or fever during pregnancy is still quite low.

 

Nor does this study point to influenza (or fever) during pregnancy as being a major cause of autism.  For now, this study only suggests that these could be two of many possible causes for the disorder.

 

And this caveat: This just one study, based on a limited cohort of subjects, that relied heavily on (potentially unreliable) self-reporting of illness/fever during pregnancy.

 

Meaning that we need to approach these findings cautiously.

 

Maggie Fox of NBC News has more on this story.

 

Flu, fever linked with autism in pregnancy study

By Maggie Fox, NBC News

Doctors trying to find some of the causes of autism put another piece into the puzzle on Monday: They found women who had flu while they were pregnant were twice as likely to have a child later diagnosed with autism. Those who had a fever lasting a week or longer -- perhaps caused by flu or maybe by something else -- were three times as likely to have an autistic child.

(Continue . . .)

 

Even without this latest study, the preponderance of evidence continues to show that pregnant women – and their unborn children – are at greater risk from influenza than most people appreciate.

 

Which is why the the CDC and other public health entities continue to stress the importance of seasonal flu vaccination for pregnant women.

 

In October of 2011, in IDSA: Flu Vaccines In Pregnancy, we saw several studies presented at the 49th Annual Meeting of the Infectious Diseases Society of America (IDSA) reaffirming the benefits and safety of maternal vaccination.

 

The CDC has synopsized these studies in:

 

Pregnancy and Influenza Vaccine Safety

 

Vaccines are drugs, and there is no such thing as a 100% safe and 100% effective drug. Even taking over-the-counter medicines entail some risks.

 

But the safety profile of flu vaccines is excellent, and serious side effects are exceedingly rare.

 

The overwhelming evidence shows that the real risk comes from the virus, not from the shot.

Federal Appeals Court Rejects Vaccine-Autism Link

 

 

 

# 4842

 

Yesterday a Federal Appeals court upheld an earlier vaccine court decision (Cedillo v. Secretary of Health and Human Services) that determined there is little if any evidence to support claims of a vaccine-autism link.

 

 

In the previous ruling (2009) Special Master Denise Vowell wrote that the evidence of any link  "is weak, contradictory and unpersuasive.”

 

In it’s ruling yesterday, the appeals court wrote “we have carefully reviewed the decision of the special master and we find that it is rationally supported by the evidence, well-articulated, and reasonable.”

 

While this won’t end the legal battles for compensation (more test cases are on the docket), this is another in a long series of setbacks for those who maintain a link exists between vaccines and autism.

 

The court’s ruling can be read in its entirety at this link.

 

 

Additional coverage of this story can be found at:

 

Autism-Vaccine Link Rejected by Appeals Court

 

Appeals court rejects autism vaccine link

 

Court finds no link between vaccines, autism