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WASHINGTON -- The most controversial and reactive of all childhood shots is the DTP inoculation, and a newer, safer version exists. So why is the old shot, although fading slowly, still in use? This simple question -- still basically unanswered by the federal public health establishment -- has engendered huge volumes of debate in recent years. And it still does, triggering accusations from critics that:

• Drug companies keep DTP alive because it is less-expensive to make, offers a bigger profit margin and can be easily dumped on developing countries.

• And federal health officials hesitate to kill it because to do so would be a tacit admission they have ordered the use of an unsafe substance for decades.

DTP stands for diphtheria, tetanus, and pertussis (or whooping cough). The protective shot, given much of this century to U.S. babies and children around the world, has been blamed by parents, their lawyers and a good many medical experts for a majority of the serious crippling and lethal reactions that rarely occur in vaccinated infants.

Here's how reactive it is in comparison to other vaccines: When Gannett News Service used the Freedom of Information Act to obtain a computer database from the National Vaccine Injury Compensation Program -- set up by Congress a decade ago to help the families of children dead or disabled after their childhood shots -- the statistics revealed fully 81 percent of the $916 million awarded in total compensation so far went for DTP cases.

The suspected culprit in DTP reactions is the pertussis portion of the inoculation -- mainly because it is made from the killed whole cells of pertussis bacteria, the walls of which contain endotoxins, or bacterial poisons released upon the cell's death. These, some scientists suspect, can disrupt blood vessels and neural transmittors to cause devastating brain damage.

``My position has always been that there is no one DTP vaccine,'' said Dr. John Menkes, a Cedars Sinai Hospital pediatric neurologist in Los Angeles who's considered one of the founders of that medical discipline. ``It differs from one manufacturer to the next, and from one batch to the next. One batch can be a bad batch, and another -- perfectly safe. I have always known that this vaccine can cause neurological reactions.''

One big problem, Menkes said, is baby doctors -- just like parents -- are rarely informed of the potential dangers of DTP. ``Pediatricians are taught that vaccines are good for babies, and that reactions are so rare they will probably not see one during their whole career as a doctor.'' This, as it turns out, is an extremely optimistic teaching.

American children -- to get into daycare centers and schools and much of the rest of accepted society -- are required to get five shots: at 2 months, at 4 months, at 6 months, at 18 months, and a booster between 4 and 6 years of age. Since 1992, the safer DTaP vaccine has been licensed by the Food and Drug Administration for vaccinating the 18-month olds and kids 4-6 years. In 1996, the FDA approved DTaP for use on the infants under 1 year of age.

The ``aP'' stands for acellular pertussis. Unlike the ``P'' component in the DTP vaccine, DTaP does not contain the toxic whole cell of the pertussis bacteria, only a few detoxified components of the bacteria that will still spark immunity. DTaP is now the ``preferred'' vaccine listed by the federal Centers for Disease Control in Atlanta. But some pediatricians prefer the older one. And many children receive the whole-cell pertussis component when they get a DTPH shot -- a combination of the DTP with a HiB vaccine that protects against haemophilus influenza type B, which can lead to meningitis.

The CDC -- which makes mass vaccine purchases for public health clinics, and state and county health departments no longer buys straight DTP, having used up its stockpile in September 1996. DTaP, however, still is not approved by the FDA for the first three combination shots with HiB at 2, 4 and 6 months. Because many pediatricians prefer to reduce office visits by giving the combined DTP-HiB shot and because many HMOs use about 50 percent DTPH, as many as 30 percent of American infants still get reactive whole-cell pertussis.

The safer acellular vaccine actually was used for about 15 years in the 1960s and early 1970s. Internal drug company memos show they knew it was less reactive. But it cost more to make and the profit margin wasn't as high. ``DTP is a much cheaper product,'' said Robert Snyder, vaccine contract officer for the CDC's National Immunization Program. Eli Lilly and Co. dropped its acellular in late 1975. And when Wyeth Laboratories tried to re-market it, the FDA refused to re-license it because the formula wasn't exactly duplicative. Pediatricians were stuck with the reactive whole-cell vaccine.

By the early 1980s, as word got around, reactions increased, children suffered, and parents began to complain and sue, the pharmaceutical companies started getting hit with huge court damages -- often more than $5 million a case. Dr. Robert Chen, chief of vaccine safety with the CDC's National Immunization Program, kept track: Lawsuits against DTP manufacturers went from four in 1980 to 255 by 1986. The big drug firms, in response, increased their DTP price from 15 cents a dose in 1980 to $7.69 in 1987.

Scientists and the federal public health community still cannot seem to agree on the relative worth and efficiency of DTP, compared to DTaP. Many Department of Health and Human Services officials think DTP offers more effective protection. The FDA sticks up for DTP at every opportunity. The agency's spokeswoman Lenore Gelb told GNS, ``The FDA considers licensed whole-cell pertussis vaccines to be safe and effective. Whole-cell vaccines have been used in the U.S. for more than 50 years and their widespread use in infants has effectively controlled the disease.''

In a Pediatrics magazine report of a study by several well known pertussis scientists, DTP comes out on top in efficiency. The study claims DTP was 84 percent efficient and the DTaP was 58 percent efficient against whooping cough of a week's duration in a study of 10,271 German infants. Against ``typical pertussis'' of 21 days, the DTP was 94 percent and the DTaP 86 percent efficacious. Yet when the National Institutes of Health did a mammoth and exhaustive 15-year study of DTP against DTaP in 24,000 infants in Italy and Sweden, the results clearly favored DTaP.

`The clinical trial we supported shows DTaP is more efficacious,'' John LaMontagne, director of the National Institutes of Health's Division of Microbiology and Infectious Diseases, said of the results announced in 1995. In all these tests, the DTaP showed far fewer side effects. DTP's potential for causing reactions compared to the newer, acellular DTaP is evident statistically in the database records of the National Vaccine Injury Compensation Program. In the 10-year history of the federal compensation program, 5,261 claims have been filed -- 3,776 of them involving the whole-cell DTP shot. The safer DTaP shot has produced four claims.

The Japanese have used DTaP exclusively since discontinuing DPT almost two decades ago in the face of severe reactions and pertussis outbreaks caused by suspicious parents who stopped vaccinating their infants. Powerful elements of the public health community are loath to cut DTP use to zero.

One reason is cost, the other is reputation. ``Whole-cell DTP can be defended because it fights disease,'' says Dr. George Peter, former editor of the tremendously influential ``Redbook'' of the American Academy of Pediatrics, the guide pediatricians heed religiously. ``We are not in a position yet to justify withdrawing it from the market. For us to take that step would mean that we would have to tell other countries in the world to stop using it. Great Britain uses it and developing countries are using it. I am not in favor of taking the vaccine off the market. I can't justify it.''

Dr. Walter Orenstein, director of the CDC's National Immunization Program, sees a day when the acellular pertussis vaccine will replace DPT. But the influential Orenstein is not sanguine with yanking the whole-cell DTP off the market. Brain damage caused by DPT ``is still in scientific dispute,'' he noted. And while ``we clearly want to move to DTaP'' in making combination vaccines, ``whole-cell DTP is an acceptable alternative.''

The chances of a serious reaction to the whole-cell shot appear to be about 1 in 62,000, pretty good odds for children. The federal health hierarchy clearly is convinced the tradeoff of notorious reactions vs. protection is worthwhile in fighting an illness that claimed about 12,000 lives a year in this country in the 1930s and now kills maybe 10.

Enough so to maintain the controversial stance that DTP is not to blame in the face of obviously serious seizures and brain damage following inoculation. The DTP may cause the fever that causes the seizure that causes the brain damage, the federal argument goes, but then any fever might start the chain. So DTP, in triggering a reaction, actually is just unmasking an underlying problem that was there all along.

Or, as the federal vaccine compensation program's chief medical officer, Dr. Geoffrey Evans contends, reactions are mostly triggered in children who are predisposed genetically to seizures, encephalopathy and the like. But don't try these arguments on the parents of dead or damaged children. They are likely to quote a version of the motto of the National Vaccine Information Center, a private group that seeks to inform parents of the risks involved: ``When it happens to you or your child, the risks are 100 percent.''
 
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