Ensuring vaccine safety and monitoring: checks and balances

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.

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