FromMedScape

Childhood asthma is reduced by half when the first dose of diphtheria, pertussis, and tetanus (DPT) is delayed by more than 2 months vs given during the recommended period, according to the results of a retrospective longitudinal study reported in the March issue of the Journal of Allergy & Clinical Immunology.

“Early childhood immunizations have been viewed as promoters of asthma development by stimulating a TH2-type immune response or decreasing microbial pressure, which shifts the balance between TH1 and TH2 immunity,” write Kara L. McDonald, MSc, from the University of Manitoba in Winnipeg, Manitoba, Canada, and colleagues. “Differing time schedules for childhood immunizations may explain the discrepant findings of an association with asthma reported in observational studies. This research was undertaken to determine whether timing of diphtheria, pertussis, tetanus (DPT) immunization has an effect on the development of childhood asthma by age 7 years.”

The investigators analyzed data from the complete immunization and healthcare records of a cohort of children born in Manitoba in 1995, from birth until age 7 years. Using multivariable logistic regression, they computed the adjusted odds ratio for asthma at age 7 years according to the timing of DPT immunization.

Among 11,531 children who received at least 4 doses of DPT, the risk for asthma was halved in children in whom administration of the first dose of DPT was delayed by more than 2 months. For children with delays in administration of all 3 doses, the likelihood of asthma was 0.39 (95% confidence interval [CI], 0.18 - 0.86).

“We found a negative association between delay in administration of the first dose of whole-cell DPT immunization in childhood and the development of asthma; the association was greater with delays in all of the first 3 doses,” the study authors write. “The mechanism for this phenomenon requires further research.”

Limitations of this study include possible ascertainment bias; findings not yet confirmed with the diphtheria, acellular pertussis, tetanus (DaPT) vaccine; and inability to refute the issue of early-life infections as an explanation for the association between delayed immunization and protection against the development of asthma.

“Further study is vital to gain a detailed understanding of the relationship between vaccination and allergic disease, because a perception that vaccination is harmful may have an adverse effect on the effectiveness of immunization programs,” the study authors conclude.

From New York Times

In a highly unusual outbreak of measles here last month, 12 children fell ill; nine of them had not been inoculated against the virus because their parents objected, and the other three were too young to receive vaccines.

The parents who objected to their children being inoculated are among a small but growing number of vaccine skeptics in California and other states who take advantage of exemptions to laws requiring vaccinations for school-age children.

The exemptions have been growing since the early 1990s at a rate that many epidemiologists, public health officials and physicians find disturbing.

Children who are not vaccinated are unnecessarily susceptible to serious illnesses, they say, but also present a danger to children who have had their shots

the measles vaccine, for instance, is only 95 percent effective

and to those children too young to receive certain vaccines.

Measles, almost wholly eradicated in the United States through vaccines, can cause pneumonia and brain swelling, which in rare cases can lead to death. The measles outbreak here alarmed public health officials, sickened babies and sent one child to the hospital.

Every state allows medical exemptions, and most permit exemptions based on religious practices. But an increasing number of the vaccine skeptics belong to a different group

those who object to the inoculations because of their personal beliefs, often related to an unproven notion that vaccines are linked to autism and other disorders.

Twenty states, including California, Ohio and Texas, allow some kind of personal exemption, according to a tally by the Johns Hopkins University.

I refuse to sacrifice my children for the greater good, said Sybil Carlson, whose 6-year-old son goes to school with several of the children hit by the measles outbreak here. The boy is immunized against some diseases but not measles, Ms. Carlson said, while his 3-year-old brother has had just one shot, protecting him against meningitis.

When I began to read about vaccines and how they work, she said, I saw medical studies, not given to use by the mainstream media, connecting them with neurological disorders, asthma and immunology.

Ms. Carlson said she understood what was at stake. I cannot deny that my child can put someone else at risk, she said.

In 1991, less than 1 percent of children in the states with personal-belief exemptions went without vaccines based on the exemption; by 2004, the most recent year for which data are available, the percentage had increased to 2.54 percent, said Saad B. Omer, an assistant scientist at the Johns Hopkins Bloomberg School of Public Health.

While nationwide over 90 percent of children old enough to receive vaccines get them, the number of exemptions worries many health officials and experts. They say that vaccines have saved countless lives, and that personal-belief exemptions are potentially dangerous and bad public policy because they are not based on sound science.

If you have clusters of exemptions, you increase the risk of exposing everyone in the community, said Dr. Omer, who has extensively studied disease outbreaks and vaccines.

It is the absence, or close to it, of some illnesses in the United States that keep some parents from opting for the shots. Worldwide, 242,000 children a year die from measles, but it used to be near one million. The deaths have dropped because of vaccination, a 68 percent decrease from 2000 to 2006.

The very success of immunizations has turned out to be an Achilles heel, said Dr. Mark Sawyer, a pediatrician and infectious disease specialist at Rady Childrens Hospital in San Diego. Most of these parents have never seen measles, and dont realize it could be a bad disease so they turn their concerns to unfounded risks. They do not perceive risk of the disease but perceive risk of the vaccine.

Dr. Sawyer and the vast majority of pediatricians believe strongly that vaccinations are the cornerstone of sound public health. Many doctors view the so-called exempters as parasites, of a sort, benefiting from the otherwise inoculated majority.

Most children get immunized to measles from a combined measles, mumps and rubella vaccine, a live virus.

While the picture of an unvaccinated child was once that of the offspring of poor and uneducated parents, exempters are often well educated and financially stable, and hold a host of like-minded child-rearing beliefs.

Vaccine skeptics provide differing explanations for their belief that vaccines may cause various illnesses and disorders, including autism.

Recent news that a federal vaccine court agreed to pay the family of an autistic child in Georgia who had an underlying mitochondrial disorder has led some skeptics to speculate that vaccines may worsen such conditions. Again, researchers say there is no evidence to support this thesis.

Alexandra Stewart, director of the Epidemiology of U.S. Immunization Law project at George Washington University, said many of these parents are influenced by misinformation obtained from Web sites that oppose vaccination.

The autism debate has convinced these parents to refuse vaccines to the detriment of their own children as well as the community, Ms. Stewart said.

While many parents meet deep resistance and even hostility from pediatricians when they choose to delay, space or reject vaccines, they are often able to find doctors who support their choice.

I do think vaccines help with the public health and helping prevent the occasional fatality, said Dr. Bob Sears, the son of the well-known child-care author by the same name, who practices pediatrics in San Clemente. Roughly 20 percent of his patients do not vaccinate, Dr. Sears said, and another 20 percent partially vaccinate.

I dont think it is such a critical public health issue that we should force parents into it, Dr. Sears said. I dont lecture the parents or try to change their mind; if they flat out tell me they understand the risks I feel that I should be very respectful of their decision.

Some parents of unvaccinated children go to great lengths to expose their children to childhood diseases to help them build natural immunities.

In the wake of last months outbreak, Linda Palmer considered sending her son to a measles party to contract the virus. Several years ago, the boy, now 12, contracted chicken pox when Ms. Palmer had him attend a gathering of children with that virus.

It is a very common thing in the natural-health oriented world, Ms. Palmer said of the parties.

She ultimately decided against the measles party for fear of having her son ostracized if he became ill.

In the late 1960s and 1970s, measles outbreaks in Alaska and California triggered strong enforcement of vaccine mandates by states, and exemption laws followed.

While the laws vary from state to state, most allow children to attend school if their parents agree to keep them home during any outbreak of illnesses prevented by vaccines. The easier it is to get an exemption

some states require barely any paperwork

the more people opt for them, according to Dr. Omers research, supported by other vaccine experts.

There are differences within states, too. There tend to be geographic clusters of exempters in certain counties or even neighborhoods or schools. According to a 2006 article in The Journal of The American Medical Association, exemption rates of 15 percent to 18 percent have been found in Ashland, Ore., and Vashon, Wash. In California, where the statewide rate is about 1.5 percent, some counties were as high as 10 percent to 19 percent of kindergartners.

In the San Diego measles outbreak, four of the cases, including the first one, came from a single charter school, and 17 children stayed home during the outbreak to avoid contracting the illness.

There is substantial evidence that communities with pools of unvaccinated clusters risk infecting a broad community that includes people who have been inoculated.

For instance, in a 2006 mumps outbreak in Iowa that infected 219 people, the majority of those sickened had been vaccinated. In a 2005 measles outbreak in Indiana, there were 34 cases, including six people who had been vaccinated.

Here in California, six pertussis outbreaks infected 24 people in 2007; only 2 of 24 were documented as having been appropriately immunized.

A surveillance program in the mid 90s in Canada of infants and preschoolers found that cases of Hib fell to between 8 and 10 cases a year from 550 a year after a vaccine program was begun, and roughly half of those cases were among children whose vaccine failed.

CDC reports more seizures seen in toddlers given combined shot; experts stress real risk is still low

From HealthDay

U.S. health officials are no longer recommending the combination MMRV (measles, mumps, rubella and varicella) vaccine over the MMR vaccine and a separate varicella vaccine for kids.

The change comes after new data show that the MMRV shot increases the risk for febrile seizure in children aged 12 to 23 months. Preliminary findings suggest there is a doubling in the relative increased risk in this age group within a week to 10 days after receiving the shot, according to a report in the March 14 issue of the Morbidity and Mortality Weekly Report, published by the U.S. Centers for Disease Control and Prevention.

Based on the preliminary data, the CDC’S Advisory Committee on Immunization Practices (ACIP) is withdrawing its preference, issued last year, for the combination vaccine over the two separate injections.

But the absolute risk of febrile seizures is still low, experts stressed.

“The relative risk doesn’t really give parents the true understanding of what’s happening,” said Dr. Robert Frenck, a professor of pediatrics at Cincinnati Children’s Hospital. “A big pediatric practice maybe has 100 newborns a month added to its practice, so that they may see one [incidence of febrile seizure related to the vaccination] a year.”

And because of manufacturing difficulties, the MMRV shot, made by Merck, won’t really be available until about this time next year, added Frenck, who is a member of the American Academy of Pediatrics’ committee on infectious diseases.

The MMRV was licensed by the U.S. Food and Drug Administration on Sept. 6, 2005, for use in children aged 12 months to 12 years. The first dose was recommended at 12 to 15 months, and the second at 4 to 6 years.

But the Vaccine Safety Datalink (VSD), which monitors vaccine safety, detected a signal for increased seizures in children aged 12 to 23 months who got the MMRV shot compared with those who got the MMR one (many children also got varicella). The MMR shot is also known to cause febrile seizures, Frenck said.

The VSD then initiated a study of 43,353 children aged 12 to 23 months who received the MMRV vaccine and 314,599 children aged 12 to 23 months who received the MMR vaccine and varicella vaccine during the same visit, according to the CDC report.

“The preliminary results indicated a rate of febrile seizure of nine per 10,000 vaccinations among MMRV vaccine recipients compared with four per 10,000 vaccinations among MMR vaccine and varicella vaccine recipients,” the CDC reported. “These results suggest that, in the 7-10 day post-vaccination period, approximately one additional febrile seizure would occur among every 2,000 children vaccinated with MMRV vaccine, compared with children vaccinated with MMR vaccine and varicella vaccine administered at the same visit.”

On Feb. 27, the ACIP was informed about the heightened risk.

Febrile seizures are convulsions brought on by fever, usually from common childhood illnesses such as middle ear infections, viral upper respiratory tract infections and roseola. Although the seizures are distressing, children generally recover, according to the CDC.

“Practically speaking, it means little,” said Dr. Paul A. Offit, director of the Vaccine Education Center and chief of infectious diseases at the Children’s Hospital of Philadelphia. “The attributable risk of fever is still quite low. I think the committee thought the better part of valor was at least not to express a preference for one over the other. For the most part, MMRV is not particularly available, so there’s little or no impact.”

There is no data yet on the risk for febrile seizures after the second MMRV vaccine, which is given at 4 to 6 years of age, although previous research showed that the second dose is less likely to cause fever than the first.

The changes have nothing to do with a possible vaccination link to autism, Frenck said.

From MedPageToday.com

Sen. John McCain, the presumptive Republican candidate for president, has given credibility to “strong evidence” of a link between autism and thimerosal in childhood vaccines. He cited “divided scientific opinion” on the matter.

“It’s indisputable that (autism) is on the rise amongst children,” McCain said in answering a question from the mother of a boy with autism at a town hall meeting. “The question is what’s causing it. And we go back and forth and there’s strong evidence that indicates that it’s got to do with a preservative in vaccines.”

The Arizona senator said there’s “divided scientific opinion” on the issue, with “many on the other side that are credible scientists that are saying that’s not the cause of it.” His remarks were first reported by ABC News.

Asked today whether McCain’s statement, made last Friday, was carefully reasoned or should be considered an off-hand remark, Douglas Holtz-Eakin, Ph.D., a senior policy adviser to the McCain campain, commented:

“Sen. McCain understands there have been numerous scientific studies that haven’t found a link. He also recognizes there are many people who’ve raised concerns about a possible link. He isn’t taking sides. Until we better understand the root causes for the rising number of diagnoses, all concerns won’t be put to rest. He’s advocating greater research.

“He had expressed sympathy for the woman’s concern. His position is to pursue sound science. He has a broad interest in this phenomenon that isn’t restricted to vaccines or preservatives.”

The CDC, FDA, World Health Organization, Institute of Medicine, and the American Academy of Pediatrics agree there is no evidence linking autism with thimerosal, the mercury-based preservative that is no longer used in many childhood vaccines.

Since the preservative was removed from all childhood vaccines in 2001, the apparent occurrence of the disorder has continued to rise.

A study of California Department of Developmental Services data published in January indicated that there was “an increase in autism in California despite the removal of thimerosal from most vaccines” (See: Autism Diagnoses Rise After End of Thimerosal in Vaccines).

If thimerosal causes autism, the prevalence of the disorder should have declined as the chemical was removed from vaccines, researchers said. No such decline occurred in this study, or in Canada, Denmark and Sweden, where thimerosal was removed during the mid-1990s.

“If Sen. McCain believes there’s a link, he’s clearly misinformed,” commented Paul Offit, M.D., a professor of pediatrics at the University of Pennsylvania and chief of infectious diseases at Children’s Hospital of Philadelphia.

“There is no debate within the medical community,” commented Dr. Offit. “There’s never been a single epidemiological study showing a link. To suggest otherwise is extremely irresponsible.”

Nonetheless, some parent activist groups and attorneys have claimed that thimerosal causes autism. Environmental lawyer Robert F. Kennedy Jr. suggests that public health officials conspired with drug makers to “poison a generation of American children.” The anti-thimerosal campaign is supported by lawyers who have filed more than 4,800 suits against vaccine-makers.

Dr. Offit and other researchers worry that unfounded reports about vaccines and autism could discourage parents from getting their children immunized. “McCain may think he’s helping by reaching out to parents of autistic kids. But he does them a tremendous disservice and can unnecessarily scare the public about the safety of vaccines,” Dr. Offit said.

McCain’s remarks were applauded by National Autism Association president Wendy Fournier. “We completely agree with him and hope he continues talking about this subject so we can get to the bottom of what’s causing this epidemic.”

Democratic hopeful Hillary Clinton announced in November that she would spend $700 million a year on autism research, teacher training, and support services. Barack Obama’s health plan has a section on autism. He’s supported federal spending on autism research on “root causes and treatments.”

From The Associated Press

Children suffered higher rates of fever-related convulsions when they got a Merck & Co. combination vaccine instead of two separate shots, according to a new study presented Wednesday.

The results prompted a federal advisory panel on vaccines to water down their preference for the combo vaccine ProQuad, which protects against measles, mumps and rubella as well as chickenpox.

In the study of children ages 12 months through 23 months, the rate of seizures was twice as high in toddlers who got ProQuad, compared with those who got one shot for chickenpox and one for the three other diseases.

The risk translates to about one extra case of convulsion for every 2,000 doses of ProQuad given said Dr. Nicola Klein, who lead the federally funded study. She presented the data at a meeting of the Advisory Committee on Immunization Practices.

The study focused on children who develop fevers and then go into convulsions

an occurrence that frightens parents but usually has no lingering consequences. There were no deaths in the new study.

ProQuad was licensed in 2005. It’s been in extremely short supply since last year, when Merck suspended production because of manufacturing problems. The company expects to resume ProQuad production next year.

The panel had previously taken a position that they preferred doctors give children as few needlesticks as possible, and that ProQuad is preferable to giving separate shots.

It voted Wednesday to amend that, to say they’re no longer voicing a preference for ProQuad over the separate shots.

“Safety, shortages, delivery issues

lots of reasons not to state such a strong preference,” said member panel Patsy Stinchfield, an infectious disease expert at Children’s Hospitals and Clinics of Minnesota.

Merck officials said their own research, though preliminary, also showed a doubling of the risk in children within five to 12 days of vaccination. However, the occurrence was low

about 5 cases in 10,000, Merck officials said.

They said there was five times more chickenpox antigen, the key ingredient, in the ProQuad shot than in the stand-alone chickenpox shot. But they said it’s not clear that would explain the difference in seizure rates.

For some reason, the difference disappears when comparing rates for 30 days, Merck officials added.

Klein’s research checked seizure rates only at seven to 10 days after vaccination, and looked at about 43,000 kids who got ProQuad and 315,000 who got the two other shots together. It found fever-related seizures occurred at a rate of 9 per 10,000 children vaccinated with ProQuad, compared with 4 per 10,000 for those who got separate shots.

Klein is co-director of Kaiser Permanente Vaccine Study Center in Oakland, Calif., one of seven sites in the study. Her work was funded by the U.S. Centers for Disease Control and Prevention.

ProQuad costs $124 per dose, about the same as the two other shots combined.