The article "Was it Murder or Was it a Vaccine?" in the September 2000 issue of Redbook Magazine makes a number of claims about the dangers of the DTP (diphtheria-tetanus-pertussis) vaccine. Much of the information in the piece is inaccurate, and may lead to confusion or unwarranted apprehension among parents.

NNii has developed responses to common questions that might arise among those who read the article. We have also listed reputable sources where more information can be found.

What is pertussis, and why is the pertussis vaccine routinely recommended for children?

• Children with pertussis (often known as whooping cough) develop thick, glue-like mucus in the windpipe, which causes severe coughing spells that make it difficult for them to eat, drink, or breathe. Sometimes the child coughs several times before breathing in, and when they do breathe, there is a loud gasp or "whooping" sound. The disease is most severe when it occurs early in life, when children with whooping cough often require hospitalization.

Pertussis is one of the most contagious human diseases, and is a great risk to those who are unvaccinated. Pertussis will develop in 90% of unvaccinated children living with someone with pertussis, and in 50% to 80% of unvaccinated children who attend school or day care with someone with pertussis. Prior to vaccination, as many as 175,000 cases of pertussis were reported in the U.S. each year, causing 8,000 deaths. Today, there are about 7,000 cases of the disease and just 10 deaths each year.

References:�

• Atkinson W, Wolfe C, Nelson R, eds. Epidemiology and Prevention of Vaccine Preventable Diseases. 6th edition (The Pink Book). Atlanta, Centers for Disease Control and Prevention, 2000. Chapter on pertussis. Also available at http://www.cdc.gov/nip/publications/pink/pert.pdf
• American Academy of Pediatrics. Committee on Infectious Diseases. Red Book: Report of the Committee on Infectious Diseases, 25th ed., Section 3, Chapter on Pertussis. Elk Grove Village, IL: American Academy of Pediatrics; 2000.

Could the DTP vaccine cause brain damage that resembles Shaken Baby Syndrome?

• No. There has never been any evidence that any vaccine leads to symptoms typical of Shaken Baby Syndrome (SBS).

SBS is a well-defined medical entity, which includes swelling of the brain, combined with bleeding within the head, as well as bleeding in the interior lining of the eyes. There may also be evidence of other trauma, such as rib and other bone fractures.

Although in very rare cases the DTP vaccine may cause inflammation of the brain and spinal cord, these symptoms are distinctly different from those of Shaken Baby Syndrome.

References:

• Chadwick DC, Kirschner RH Reece RM et al. Shaken Baby Syndrome: A Forensic Pediatric Response. Pediatrics 1998;101 :321-22.
• Corsellis JAN, Janota I, and Marshall AK. Immunization against whooping cough: a neuropathological review. Neuropathology and Applied Neurobiology 9: 261-270. 1983.
• Lancon JA, Haines DE, and Parent AD. Anatomy of the Shaken Baby Syndrome.Anatomical Record (New Anatomist) 1998;253:13-18.
• Fenichel GM. Neurological Complications of Immunization. Annals of Neurology 1982;12:119-128.
• Fulginiti VA. A Pertussis Vaccine Myth Dies. American Journal of Diseases of Childhood 1990;144:860-861.
• Gale JL, Thapa PB, Wassilak SGF et al. Risk of Serious Acute Neurological Illness After Immunization with Diphtheria-Tetanus-Pertussis Vaccine: A Population-Based Case-Control Study. JAMA 1994; 271:37-41.
• Griffin MR, Ray WA, Mortimer TA et al. Risk of Seizures and Encephalopathy After Immunization with the Diphtheria-Tetanus-Pertussis Vaccine. JAMA 1990;263: 1641-1654.
• Institute of Medicine. Adverse Effects of Pertussis and Rubella Vaccines. National Academy Press. Washington, DC. 1991.
• Altman RL, Kutsher MS, and Brand DA. The Shaken Baby Syndrome (letter). New England Journal of Medicine. 1998;339: 1329-30.

Can the pertussis portion of the DTP vaccine cause infection that is similar to meningitis?

• No. Neither the DTP vaccine nor the (currently recommended) DTaP vaccine contains living organisms. The pertussis portion is derived from cultures of Bordatella pertussis, the bacterium that causes whooping cough. The bacteria are inactivated as one of the first steps in the manufacturing process. The fragments of the bacterial cell that remain in the vaccine stimulate the immune system to develop antibodies that will protect against future invasion by this bacterium. However, since the bacteria are inactivated, none of these fragments�- alone or in combination�- can grow. Therefore, there is no way that they can cause an infection that resembles meningitis.

References:

• Parkman PD, Hardegree MC. Regulation and Testing of Vaccines. In: Vaccines 3rd edition (SA Plotkin and WA Orenstein, editors). W.B. Saunders Company. 1999.
• Paoletti LC and McInnes (editors). Vaccines -- from Concept to Clinic: a guide to the development and clinical testing of vaccines for human use. CRC Press, 1999.

Why doesn't the government ban the DTP vaccine if the DTaP vaccine is safer?

• As with all pharmaceutical products, there is a continual desire to improve vaccines -- to make them safer, more effective and easier to administer.

Whole cell pertussis vaccines (DTP) are extremely safe and effective. More than half of those immunized experience no side effects at all. Most side effects are very mild, such as fever or soreness at the injection site. However, because these uncomfortable mild reactions and other rare but severe reactions (such as seizures) do occur following the DTP vaccine, research continued to develop a vaccine that would cause fewer side effects. The acellular pertussis vaccines (DTaP) were the result of this research.

Acellular pertussis vaccines (DTaP) are now recommended for all children in the U.S. because they are better tolerated by children, not because the whole cell pertussis vaccines are unsafe. In fact, most countries in the world routinely use the whole cell vaccines. For example, this is the vaccine used in England and France for primary immunization of all infants and is the vaccine used by the World Health Organization's Expanded Program of Immunization.

References:

• World Health Organization web site:
• http://www.who.int/vaccines-diseases/diseases/pertussisvaccine.htm
• Department of Health (UK): Immunization Against Infectious Diseases: 1996.DM Salisbury and NT Begg, Editors. HMSO Publications. London, England.
• CDC web site: http://www.cdc.gov/nip/publications/pink/pert.pdf�

What is the chance that my child might have a serious adverse reaction to the DTP or DTaP vaccine?

• If immunized in the U.S., you child is almost certain to receive DTaP rather than DTP because DTaP has been recommended for use for all children in the U.S. since 1997. You can check with your child's health care provider to be certain.
• Millions of doses of DTaP have been given to American children since the Food and Drug Administration (FDA) approved this vaccine in 1991. Adverse events that occur after vaccination are reported to the Vaccine Adverse Event Reporting System (VAERS). With DTaP, fewer than 0.3 serious adverse events are reported per 10,000 children vaccinated. With DTP, about 1 serious adverse event was reported per 10,000 children vaccinated.
• Conversely, about 5% (500 out of 10,000) of children who develop diphtheria, 3% of children who develop tetanus, and 0.5% of children who develop pertussis will die from the diseases, and many more will suffer permanent damage.

Reference:

• Rosenthal S, Chen R, Hadler S. The safety of acellular pertussis vaccine vs. whole-cell pertussis vaccine. A postmarketing assessment. Arch Pediatr Adolesc Med 1996;150:457-460.

Are there "hot lots" of vaccines that cause more side effects than others?

• Every lot of vaccine goes through exhaustive testing before it is released onto the market. Samples of each lot are tested for safety, potency, and purity before the lot may be given to patients. While there may be some lot-to-lot variation, no lot is released for use by the FDA unless it meets established criteria.
• FDA officials routinely monitor vaccine lots using Vaccine Adverse Event Reporting System (VAERS) data and other information. With the exception of an early lot of polio vaccine in 1955, which was not fully inactivated, there has never been a "hot lot" identified in U.S. licensed vaccines.
• VAERS data can be used to monitor how many adverse events have been reported for each vaccine "lot" approved for use. However, because vaccine lots are not all of the same size, nor distributed and used at the same rate, differences in the numbers of adverse events reported must be interpreted with great caution. Some people have misinterpreted the difference between the number of adverse events in some lots versus other lots as meaning that some lots�- i.e., "hot lots"�- are more dangerous than others.
• Members of the public can view the adverse reaction data in the VAERS database online. Currently, however, it is difficult to interpret this information because the number of doses created in a given vaccine lot and the actual use, or market share, is considered to be the proprietary information of the manufacturer, and as a result, is not made available to the public.
• The VAERS telephone number is 1-800-822-7967; the Web site is www.fda.gov/cber/vaers; and the email address is [email protected].

Reference:

• Parkman PD, Hardegree MC. Regulation and Testing of Vaccines. In: Vaccines 3rd edition (SA Plotkin and WA Orenstein, editors). W.B. Saunders Company.1999.

What are the current recommendations for the use of pertussis-containing vaccines?

• Since 1997, acellular pertussis vaccines have been recommended for the entire series of immunizations for all infants in the United States.

The first acellular pertussis vaccines were licensed by the Food and Drug Administration in 1991. Initially, they were licensed only for the 4th and 5th doses of the pertussis immunization series; however, they were licensed for use for the entire series in1996. Currently, there are four licensed acellular pertussis vaccines (combined with diphtheria and tetanus toxoids) available for use in the United States.

How does the government monitor vaccine safety?

• The Food and Drug Administration (FDA) regulates vaccines that are used in the United States, ensuring that they are shown to be safe and effective before they are approved for use. The vaccine first undergoes laboratory studies, then studies with animals, and then with humans. Typically, vaccines are tested in adults before they are evaluated in infants and children. The results of the studies at every step in the process must show that the vaccine does what it is supposed to do, and that it does not harm people who receive it.

Only after the FDA approves the vaccine for use in humans is the manufacturer allowed to market the vaccine. Each lot of vaccine made by the manufacturer is tested for safety, potency, and purity before being put on the market and a sample from each lot is routinely sent to the FDA. The FDA also regularly inspects the manufacturing facility and makes sure the vaccine is made in a safe and consistent manner.

In 1990, the FDA and the Centers for Disease Control and Prevention (CDC) established the Vaccine Adverse Events Reporting System (VAERS) so that reports of possible adverse reactions could be collected and analyzed. As many as 12,000 reports have been made in a single year, and about 2,000 of these reported serious illness or death. All reports are entered into a database; FDA and CDC use the data to monitor vaccine safety and conduct research studies. However, with further examination, most of these reported events have been found to be unrelated to vaccines. VAERS reports do not establish cause and effect. VAERS reports, however, are useful for generating "signals" that may require further investigation. These "signals" can then be evaluated in large epidemiological studies that can be used to determine whether the vaccine caused the adverse event.

To ensure that all relevant data are captured, VAERS allows anyone to file a report if they suspect that their child or patient has a vaccine-related reaction. Because entries are not screened, the database contains both events that are related and unrelated to vaccines. FDA and CDC monitor VAERS to determine whether any vaccine is associated with more adverse events than would be expected due to chance.

Reference:

• Chen, RT, Hibbs B. Vaccine Safety: current and future challenges. Pediatrics Ann 1998 Jul:27(7): 445-55.

What happens if a vaccine is found to cause a serious adverse event?

• When the VAERS data "signals" a potential safety problem, the suspected vaccine is thoroughly investigated through other research methods. This is because adverse events reports to VAERS are self-reported and not routinely verified before being entered into the system, thus great caution must be used in interpreting patterns found in the data. Verification studies have shown that most adverse events reported in the VAERS database are not actually caused by an immunization. Rather, the "adverse events" that are shown to be unrelated to an immunization were the result of some other cause, such as a naturally occurring illness.

Some vaccines do cause serious adverse events. However it is important to understand that the risk of serious adverse events is extremely small (approximately 1 serious event occurs for each 100,000 doses of vaccine given). Most adverse events associated with vaccines are minor and short-lived. Of those few serious adverse events which do occur, only a small proportion result in long-lasting impairment or death. The diseases that vaccines prevent are far more dangerous than the vaccines that effectively prevent them.

It is possible, however, that a vaccine could cause serious adverse events that were not previously known, or be causing them more frequently than was anticipated in the original research used to license the product. In the few cases when this has happened, the vaccine has been withdrawn from the market.

The withdrawal of the rotavirus vaccine is a recent example of this happening. Analysis of VAERS data in 1999 identified that 15 cases of a rare but serious bowel obstruction were reported in association with the rotavirus vaccine (after approximately 1.5 million doses of the newly licensed vaccine had been given to patients). Medical experts are now conducting further studies to better understand the relationship between the bowel obstructions and the vaccine. In the meantime, the vaccine has been withdrawn from use in the United States.

Reference:

• Centers for Disease Control and Prevention. Intussusception among recipients of rotavirus vaccine - United States, 1998-1999. MMWR Morb Mortal Wkly Rep 48:577-581.

Is it safe to give my child more than one vaccine at a time?

• Yes. Typically, only vaccines that have been shown to be safe and effective when given together are given at the same time. When new vaccines are evaluated, they are given along with all of the recommended childhood vaccines. Therefore, during the process of testing a potential new vaccine, its safety is assessed in the context of all other recommended vaccines.

Combination vaccines (e.g., DTP) have been used safely since the 1940s. Safety testing is performed for all combination vaccines before they are approved by the Food and Drug Administration, and available scientific studies have shown that it is not harmful to give multiple vaccines at the same time.

When it can be done safely, multiple vaccines are given in one shot as a combination vaccine. This reduces both children's discomfort by reducing the number of shots they receive, as well as the number of office visits required.

In addition to combination vaccines, a number of vaccines may be given separately but during the same office visit. Giving multiple vaccines at one time may keep children safer by protecting them against more diseases sooner.

Can my child's immune system be overloaded by giving too many vaccines at once?

• No. Infants and children are bombarded with germs every day in the air they breathe and the food they eat, but their immune systems are able to handle these exposures. Vaccination does not overburden a child's immune system; rather, it strengthens their developing immune system.

Scientists estimate that the immune system can recognize and respond to hundreds of thousands, if not millions, of different organisms. The vaccines that are recommended for all children use only a small portion of the immune system's "memory."

Reference:

• Institute of Medicine: Adverse Events Associated with Childhood Vaccines: Evidence Bearing on Causality. National Academy Press. Washington, DC. 1994.

Recommended books and Web sites:

• Offit PA and Bell LM. Vaccines: What Every Parent Should Know, revised edition. New York: IDG Books; 1999.
• Humiston SG and Good C. Vaccinating Your Child: Questions & answers for the Concerned Parent. Atlanta: Peachtree Publishers; 2000.
• American Academy of Pediatrics (www.aap.org).
• Centers for Disease Control and Prevention (www.cdc.gov/nip).