The challenge is to reduce the number of injections and minimize the side effects without compromising effectiveness and patient acceptability. Before the FDA can license any vaccine, however, it must be assessed for safety and efficacy. Postlicensure studies continue to monitor vaccine safety. Given the potential for problems and adverse effects from vaccines, Congress passed the 1986 National Childhood Vaccine Injury Act, which was spearheaded by parents who were troubled by a putative link between vaccination and neurological problems. Essentially, the act was designed to reduce the potential financial liability of vaccine makers due to vaccine injury claims and established a no-fault system for litigating claims against vaccine manufacturers.

Mounting potential liabilities totaling in the tens of billions of dollars posed financial threats to the pharmaceutical companies who produced vaccines. Vaccine makers indicated that they would cease production if this protection under the law was not enacted. The argument was that public health safety depended on the financial viability of pharmaceutical companies whose ability to produce sufficient supplies of vaccines could be imperiled by civil litigation on behalf of vaccine injury victims.

The act also mandated that all health care providers and manufacturers report certain adverse events following vaccinations to the Vaccine Adverse Event Reporting System (VAERS).

Through VAERS, jointly operated by the FDA and the CDC to monitor the safety of licensed vaccines, experts look for patterns and any unusual trends that may raise questions about a vaccine’s safety once it is used more widely in the population. The FDA continuously reviews and evaluates individual reports, in addition to monitoring overall reporting patterns. The FDA monitors reporting trends for individual vaccine lots. Most reports come from health care providers, but anyone can report an unexpected event after vaccination to VAERS. VAERS’ role is to generate new hypotheses about the cause of adverse events. For example, in August 1998, a vaccine against the rotavirus became available and infants were immunized. Within a few months, VAERS received reports that 15 infants developed a rare intestinal condition shortly after receiving the rotavirus vaccine.

Although the number was very small in comparison to the number of infants who received the injection, analysis of the VAERS reports and other data suggested that the vaccine could be associated with an increase in the risk of this rare complication and in October 1999 the vaccine was discontinued pending further study.

The Clinical Immunization Safety Assessment Centers provide an additional level of scrutiny for selected patients whose symptoms or diagnoses may represent a new adverse event. The Vaccine Safety Datalink provides data from a variety of sources, including immunization records, hospital discharge records, and mortality data.

In 1988, a National Vaccine Injury Compensation Program was created. The program is a federal “no-fault” system designed to compensate those individuals or families of individuals who have been injured by childhood vaccines. A claim may be made for any injury or death thought to be the result of a vaccine covered under the program. The U.S. Department of Health and Human Services, the U.S. Court of Federal Claims, and the U.S. Department of Justice administer the program. But, the program stipulated that all claims against vaccine manufacturers could not be heard in state or federal court, but had to be heard in the U.S. Court of Federal Claims, often referred to as the “vaccine court.” Cases are heard without juries, and awards damages are typically far below damage awards rendered in other courts.

Recently, the vaccine court has come under criticism,[64] with controversy surrounding the highly publicized case of Atlanta child Hannah Poling. In March 2008, it became public that the court had settled a case brought by Poling’s parents, who claimed that she had been diagnosed with autism after receiving five vaccinations against nine infectious diseases in 2000. In the settlement, government lawyers concluded only that the vaccines aggravated an underlying mitochondrial disorder the child already had,  which affects the ability of the body’s cells to produce energy.[65] The CDC was quick to emphasize that compensating the Poling family was not an admission that vaccines may cause autism, but vaccine critics immediately claimed vindication, and many parents expressed newfound concern. Scientists have suggested that the vaccine court has reduced the required burden of proof that vaccines caused harm, ruling in favor of families even if the majority of epidemiologic evidence refutes their claims.[66] This debate continues, as the vaccine court is currently hearing the cases of 4,800 additional autistic children whose parents claim that thimerosal caused their disease, and the court was scheduled to hear cases about whether the MMR vaccine alone can cause autism.[64] In February 2009, the vaccine court ruled in the first three of these cases that neither the vaccine nor thimerosal was responsible for the children’s autism.[67]

In 2006 the U.S. Fifth Circuit Court of Appeals ruled that plaintiffs suing three manufacturers of thimerosal could litigate in either state or federal court. This ruling was significant for the fact that the Fifth Circuit Court concluded that thimerosal is not a vaccine but a preservative and that manufacturers cannot share in the protection afforded by the no-fault system of the National Childhood Vaccine Injury Act.

Recently, the Georgia Supreme Court became the first to allow a state case against a thimerosal manufacturer to go to trial.[68]

Globally, the WHO has taken steps to ensure vaccine safety by establishing in 1999 the Global Advisory Committee on Vaccine Safety.[69] This committee is charged with advising the WHO on vaccine-related safety issues to enable WHO to respond promptly to issues of vaccine safety. The committee assesses the implications of vaccine safety worldwide and has weighed in on all of the important vaccine controversies, including MMR and autism, the safety of the mumps vaccine, thimerosalcontaining vaccines, and the safety of influenza vaccination for pregnant women.

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Tony Rosen, MPH, MD
Tony Rosen, Division of Geriatric Medicine and Gerontology, Weill Cornell Medical College, Cornell University, New York, New York;

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2. US Centers for Disease Control and Prevention. Ten great public health achievements in the twentieth century, 1900-1999.
3.   Parker AA. Implications of a 2005 measles outbreak in Indiana for sustained elimination of measles in the United States. New Engl J Med. 2006;355:1184.
4. Okonek BAM, Peters PM. Vaccines: how and why
5. Baxby D. Vaccination: Jenner’s Legacy. Berkeley, UK: Jenner Educational Trust; 1994. 6. Parish HJ. A History of Immunization. Edinburgh, UK: Livingstone; 1965.
6. Gross CP, Sepkowitz K. The myth of the medical breakthrough: smallpox, vaccination, and Jenner reconsidered. Int J Infect Dis. 1998;3:54-60.
7. Salmon DA,  et al.  Compulsory vaccination and conscientious or philosophical exemptions: past, present, and future. Lancet. 2006;367(9508):436-442.

Full References  »