The Flu Shot
By Christina Elston
There's New Debate Over whether This Year's Vaccine Puts Kids at Risk
Last winter, Daphne Allen seriously considered taking her 3-year-old daughter in to get a flu shot. "My mother lives with us, and she has emphysema," says Allen, who was concerned that her little girl might get the flu at daycare, spread it around the family and put Allen's mother at risk for complications.
The 2003-2004 flu season began and peaked earlier than usual. It was also more severe, according to the U.S. Centers for Disease Control (CDC). As national headlines tracked the number of child deaths from the illness, parents scrambled for flu shots and, in many cases, healthcare providers ran out of the vaccine. In all, 152 children died as a result of the flu, with 41 percent of them being under the age of 2, the CDC reports.
But despite the public's alarm, the only children for whom flu shots were recommended last season were those with heart, respiratory or immune disorders (the same was true for adults, although shots were recommended for any seniors over 65). Allen ultimately decided not to have her daughter vaccinated.
This season, however, things are different.
For the first time, the CDC is recommending that otherwise healthy children ages 6 months to 24 months, pregnant women and everyone in those households get flu shots. What the CDC isn't going out of its way to publicize is the fact that some of the flu shots available still contain thimerosal – a controversial, mercury-containing ingredient recently removed from all other childhood vaccines.
Mercury-free vaccines also will be available, but many public health officials say those will be reserved for pregnant women and kids under age 2, for whom mercury poses the biggest health risk. That means that kids over age 2, such as Allen's daughter, could end up getting a vaccine with thimerosal.
"I understand that they don't want to sound an alarm that will prevent parents from having their children vaccinated," Allen says of federal health officials' reluctance to publicize recommendations that parents avoid shots containing mercury. But given the choice, she says, she would prefer that her children's vaccines be mercury-free.
Heavy Metal
Thimerosal has been used in vaccines since the 1930s, according to Marie McCormick, M.D., a professor of maternal and child health at the Harvard School of Public Health. It is a preservative used to help protect vaccines – especially those stored in multiple-dose vials –
Did You Know …Other Sources of Mercury against contamination with bacteria.
Though it has been removed from other vaccines recommended for kids, thimerosal is still used in some flu vaccines because it's the only way to safely make use of multidose vials. The vials are considered more space- and cost-efficient when it comes to vaccinating large numbers of people on a seasonal basis.
Anyone can request a flu vaccine for themselves or their child (except for infants under 6 months). For years, however, flu shots were recommended only for adults, for whom thimerosal doesn't present the same health risk. This season's changed flu vaccine recommendations for kids under age 2 will mean that more mercury-free vaccine is produced. But there will likely be production of the thimerosal-containing multidose vials as well.
The downside of thimerosal is that it contains an organic form of mercury, a heavy metal that is toxic in high enough doses. The biggest danger is to unborn babies and young children, says David Carpenter, M.D., of the Institute for Health and the Environment at the State University of New York "There's very strong evidence that exposure, especially before birth, causes a reduction in IQ," Carpenter says. The effects are similar to those observed in children exposed to high levels of lead or PCBs.
While no one denies that mercury is harmful, the dispute within the healthcare community is over whether the thimerosal in vaccines contains enough mercury to cause harm. "The question is, 'Is the concentration adequate to cause effects on learning and memory in children receiving these vaccines?'" Carpenter says.
Already, some public health departments are saying they will dedicate their mercury-free flu vaccine supply to pregnant women and kids under age 2. And many public health officials also say there will be mercury-free shots available for parents who seek them out. The key for parents is to have enough information to decide whether to request a mercury-free vaccine for their kids.
A History of Controversy
The issue of mercury in vaccines first began to draw attention around 1997, when the Food and Drug Administration (FDA) Modernization Act required manufacturers to disclose the amount of mercury in each dose, says McCormick. Health officials discovered that the total amount of mercury in all of the vaccines children received exceeded an Environmental Protection Agency (EPA) standard for mercury exposure.
By 1999, reports of increasing U.S. autism rates began to emerge. The California State Department of Developmental Services documented a 273 percent increase in cases of autism between 1987 and 1998. As suspicions began to arise about a possible link, some public health experts began advocating for the removal of thimerosal from vaccines, and the CDC announced it would begin phasing out its use.
At the time, McCormick explains, virtually nothing was known about how the body metabolizes mercury. "It was taken out as a precaution," she says.
The Autism Question
Is there really a link between childhood vaccines and autism? In May, a committee of the Institute of Medicine (IOM) of the National Academy of Sciences, headed by McCormick, released a report stating that there is not. "In the doses that are being given in the vaccine schedule, there was no link between thimerosal and autism," she says.
But that report, based largely on five studies completed since 2001, has been criticized by autism activists, who charge that researchers on some of the studies were employed by vaccine companies and had a vested interest in finding no association between thimerosal and autism. Some of the studies were also conducted on populations that autism activists say received less mercury in vaccinations than did children in the United States.
But McCormick defends the IOM report and those who helped create it. She says that all researchers were required to disclose potential conflicts of interest before delivering their information. IOM committee members were selected to have the minimum conflict of interest possible, she says. They were not allowed to have:
• worked for the CDC or vaccine companies,
• made public statements about vaccines, or
• had research funded by vaccine companies.
IOM members made their decisions based strictly on the data they examined, McCormick says. "None have been able to critique the honesty of the committee."
Another objection from the autism community, however, is that the report did not address the role of genetics. Studies have shown that people's ability to clear mercury from their bodies differs depending on their genetic makeup, says Lyn Redwood, R.N., president of the Coalition for SafeMinds, a nonprofit organization dedicated to removing mercury from medical products.
"What we've been saying all along is that some infants are more susceptible to this than others," says Redwood, whose son has autism. The IOM report, she says, acknowledges that the studies from which it drew its conclusions would not detect an association between thimerosal and autism in children who were genetically less able to metabolize mercury.
In June, a Columbia University study published online in the Nature publication Molecular Psychiatry – and sponsored in part by the Coalition for SafeMinds – concluded that injecting genetically susceptible mice with thimerosal could lead to autism-like damage to the brain. Researchers reported that these mice exhibited features of autism spectrum disorders, including abnormal responses to new environments, abnormalities in brain structure and increased brain size.
Florida Congressman David Weldon, a physician, says a study that he believes "will truly answer the question of whether thimerosal is harmful to kids" is going to play out during the next 12 to 18 months. Because thimerosal was basically stripped from the childhood vaccination schedule by the year 2002, the first generation of kids in many years to grow up thimerosal-free is old enough for cases of autism – usually diagnosed after age 2 – to become apparent.
"We should begin to see a decline in autism in the next six to eight months," Weldon says. He introduced legislation this year that would have legally banned the use of thimerosal in any childhood vaccines, but the bill was not passed prior to the end of the legislative session.
This past July, the California State Department of Developmental Services (DDS) reported a nine-month sustained reduction in the number of professionally diagnosed cases of autism entering the state's developmental services system. Weldon calls this data too preliminary to be conclusive, but he says that if these results are mirrored in the rest of the country, "the case will be closed. That will be fairly compelling to most people."
Risks of Not Vaccinating
With all the controversy over thimerosal, should you even chance a flu vaccine that contains the substance? It's this question that prompts some of the strongest debate over the issue.
First, the flu is serious business. Despite the controversy, the CDC had clear reasons for its recommendations, particularly after such a deadly outbreak last season. Doctors, in fact, are generally in favor of the recommendation for flu shots.
"I think it's a good recommendation, and I support it," says Jane Siegel, M.D., head of the Infection Control Committee at Children's Medical Center in Dallas. "In children, influenza is a serious disease worth preventing."
Serious complications from the flu can occur in pregnant women and children under age 2, just as they can for people over age 65. But aside from any people living in the same households as these at-risk populations, there is no official recommendation for vaccinating healthy people ages 2 to 64. Certainly, a flu vaccine is beneficial for these folks. But considering inadequate supplies in many areas last season, parents may find their healthcare providers reserving mercury-free flu shots for kids under age 2.
Second, the flu vaccine is effective. Flu presents a special challenge to vaccine makers, according to Debra Ritzwoller, Ph.D., a researcher from Kaiser Permanente's clinical research unit in Denver, because flu strains are always changing. Vaccine makers base each year's vaccine on strains observed the previous winter, and the effectiveness of the vaccine depends on the "match" between vaccine and flu strains.
Even though there was a slight mismatch between the vaccine and flu strains last season, a research team co-lead by Ritzwoller found that the vaccine was still effective:
• Children under age 10 who had received two doses of flu vaccine were 27 percent to 50 percent less likely to visit the doctor for flu symptoms than unvaccinated children.
• Children ages 6 months to 23 months who had two doses of the vaccine were 49 percent less likely to contract flu or pneumonia than unvaccinated children.
Ritzwoller reminds parents that children who have never had a flu shot before need a booster a few weeks after their initial shot. The Kaiser study found that children receiving just one dose were not protected. "It was only effective for those kids who got the full dose," she says.
Vaccine Alternatives
Not all flu vaccines contain thimerosal, and you can request a thimerosal-free vaccine from your healthcare provider. According to the FDA, the following products are available:
Fluzone – Available in three forms: a 10-dose vial that contains thimerosal, a single-dose prefilled syringe that contains thimerosal, and a single-dose prefilled syringe that contains only trace amounts remaining from the production process.
Fluvirin – Available in two forms: a 10-dose vial that contains thimerosal, and a single-dose prefilled syringe that contains only traces.
FluMist – Available for ages 5 and up in a single-dose nasal sprayer. Contains no thimerosal.
CDC spokesperson Curtis Allen says there should be an adequate supply of mercury-free vaccine for those who want it. The agency has contracted to purchase up to 3 million doses, which Allen says should cover many of the 4.8 million children the agency is estimating will actually get flu shots.
Coalition for SafeMinds' Lyn Redwood suggests calling your healthcare provider well in advance to ask specifically which brand of vaccine the office ordered, and in which formulation. Your local health department might also be able to help you locate healthcare providers who have ordered mercury-free vaccine.
Resources
CDC Flu Hotline – 800-232-2522; www.cdc.gov/flu – The CDC's flu vaccination campaign Web site includes information about vaccines and the flu itself, including prevention tips.
KidsHealth.org – The Nemours Foundation health site includes current information on influenza and many other childhood illnesses.
National Vaccine Information Center – 703-938-0342; www.909shot.com – Focuses on the reporting and prevention of vaccine injuries and deaths. The Web site includes information on the debate over whether certain vaccines are linked to autism.
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