Like any medicine there is not perfect one, but the benefits typically out weigh the risks.
By Laura A. Stokowski, RN, MS
Staff Nurse, Inova Fairfax Hospital for Children, Falls Church, Virginia; Editor, Medscape Ask the Experts Advanced Practice Nurses
The nation’s voluntary reporting system for adverse events following vaccine administration confirms that vaccine side effects are surprisingly uncommon. Vaccine Adverse Event Reporting System (VAERS) data reveal that 11.4 adverse events occur per 100,000 vaccine doses distributed. Adverse events often depend upon the nature of the vaccine itself. The events and the frequency of events are similar to those that occur with placebo injections in controlled trials and include pain, swelling, and redness at the injection site. (Zhou W, Pool V, Iskander JK, et al. Surveillance for safety after immunization: Vaccine Adverse Event Reporting System)
Most adverse reactions to vaccines can be classified into 3 groups:
1. Vaccine-induced (eg, pain at the injection site, allergic reactions);
2. Programmatic error (eg, administering an intramuscular vaccine by the subcutaneous route); or
3. Coincidental (having a temporal association with the vaccine but would have occurred even in the absence of vaccination).
VAERS is a national “early warning” reporting system that accepts and monitors reports on adverse health effects following immunization. Jointly administered by the CDC and the FDA, VAERS was established in 1990 to provide a mechanism for the collection and analysis of adverse events associated with vaccines currently licensed in the United States. Adverse events are defined as detrimental health effects that occur after immunization that may or may not be related to the vaccine. VAERS data are continually monitored in order meet the following primary objectives:
· Detect new, unusual, or rare adverse events;
· Monitor increases in known adverse events;
· Determine patient risk factors for particular types of adverse events;
· Identify vaccine lots with increased numbers or types of reported adverse events; and
· Assess the safety of newly licensed vaccines.
VAERS is passive in the sense that it depends upon health professionals, vaccine manufacturers, or members of the public to submit reports of suspected adverse events—VAERS does not solicit reports from immunizing clinics or agencies. For this reason, the greatest weakness of the VAERS program is underreporting of events. (Each VIS gives information about VAERS and how to file a report, including the toll-free number and the Web site address.)
Data collected from 1991 to 2001 revealed that VAERS reports were received primarily from vaccine manufacturers (36.2%), state and local health departments (27.6%), and healthcare providers (20%). Only 4.2% were submitted by parents or patients, with the remaining 7.3% attributed to others.
“The simple fact,” said Tamara Tempfer, RNC, MSN, PNP, “is that healthcare providers, including nurses, just aren’t reporting adverse events.” Tempfer, a member of the US Department of Health and Human Services, Health Resource and Services Administration’s Advisory Commission on Childhood Vaccines, continued, “Practitioners who are aware of any kind of significant event following a vaccine should be reporting it.” This means any clinically important medical event that occurs after vaccination, even if the reporting person can’t be certain that the event was caused by the vaccine.
In a review of the VAERS database from 1991 to 2002, the most frequently reported adverse event was fever (25.8% of all reports), followed by injection-site hypersensitivity (15.8%), unspecified rash (11.0%), injection-site edema (10.8%), and vasodilatation (10.8%). A total of 14.2% of all reports described serious adverse events, which by regulatory definition included life-threatening illness, hospitalization or prolongation of hospitalization, permanent disability, or death. (Edlich RF, Olson DM, Olson BM, et al. Update on the National Vaccine Injury Compensation Program. J Emerg Med).
A report to VAERS is, however, just that—a report. It cannot establish a cause-and-effect relationship between an adverse effect and the vaccine that preceded it. (Varricchio F, Iskander J, Destefano F, et al. Understanding vaccine safety information from the Vaccine Adverse Event Reporting System).
Limitations of passive surveillance programs like the VAERS are the reporting of temporal or coincidental associations, unconfirmed diagnoses, and lack of denominator data and unbiased comparison groups. Basically, VAERS data raise the red flag, leading to the kind of rigorous, controlled studies that will determine if actual causation exists. (Miller ER, Iksander J, Pickering S, Varricchio F. How can you promote vaccine safety?)
VAERS was instrumental in identifying the potentially serious complication of intussusception following the first rotavirus vaccine, which is no longer licensed or available.( Iskander JK, Miller ER, Chen RT. The role of the Vaccine Adverse Event Reporting System (VAERS) in monitoring vaccine safety)
Why aren’t these adverse effects identified before the vaccine goes to market? Elaine Miller, who works with the VAERS program at the CDC Immunization Safety Office, explained, “Vaccines undergo extensive clinical evaluation of safety and efficacy in stages over several years prior to licensure. However, rarer side effects or events may occur only in a sub-group of the population that was not represented in pre-marketing studies, and may show up only after the vaccine is licensed for the general public’s use.”
