The current increase in measles cases in the United States has sharpened the focus on antivaccine activities. While the percentage of US children who are fully vaccinated remains high (≥ 94%), the number of un- or undervaccinated children has been growing1 because of nonmedical exemptions from school vaccine requirements due to concerns about vaccine safety and an underappreciation of the benefits of vaccines. Family physicians need to be conversant with several important aspects of this matter, including the magnitude of benefits provided by childhood vaccines, as well as the systems already in place for
- assessing vaccine effectiveness and safety,
- making recommendations on the use of vaccines,
- monitoring safety after vaccine approval, and
- compensating those affected by rare but serious vaccine-related adverse events (AEs).
Familiarity with these issues will allow for informed discussions with parents who are vaccine hesitant and with those who have read or heard inaccurate information.
The benefits of vaccines are indisputable
In 1999, the Centers for Disease Control and Prevention (CDC) published a list of 9 selected childhood infectious diseases and compared their incidences before and after immunization was available.2 Each of these infections causes morbidity, sequelae, and mortality at predictable rates depending on the infectious agent. The comparisons were dramatic: Measles, with a baseline annual morbidity of 503,282 cases, fell to just 89 cases; poliomyelitis decreased from 16,316 to 0; and Haemophilus influenzae type b declined from 20,000 to 54. In a 2014 analysis, the CDC stated that “among 78.6 million children born during 1994–2013, routine childhood immunization was estimated to prevent 322 million illnesses (averaging 4.1 illnesses per child) and 21 million hospitalizations (0.27 per child) over the course of their lifetimes and avert 732,000 premature deaths from vaccine-preventable illnesses” (TABLE).3
It is not unusual to hear a vaccine opponent say that childhood infectious diseases are not serious and that it is better for a child to contract the infection and let the immune system fight it naturally. Measles is often used as an example. This argument ignores some important aspects of vaccine benefits.
It is true in the United States that the average child who contracts measles will recover from it and not suffer immediate or long-term effects. However, it is also true that measles has a hospitalization rate of about 20% and a death rate of between 1/500 and 1/1000 cases.4 Mortality is much higher in developing countries. Prior to widespread use of measles vaccine, hundreds of thousands of cases of measles occurred each year. That translated into hundreds of preventable child deaths per year. An individual case does not tell the full story about the public health impact of infectious illnesses.
In addition, there are often unappreciated sequelae from child infections, such as shingles occurring years after resolution of a chickenpox infection. There are also societal consequences of child infections, such as deafness from congenital rubella and intergenerational transfer of infectious agents to family members at risk for serious consequences (influenza from a child to a grandparent). Finally, infected children pose a risk to those who cannot be vaccinated because of immune deficiencies and other medical conditions.
A multilayered US system monitors vaccine safety
Responsibility for assuring the safety of vaccines lies with the US Food and Drug Administration (FDA) Center for Biologics Evaluation and Research and with the CDC’s Immunization Safety Office (ISO). The FDA is responsible for the initial assessment of the effectiveness and safety of new vaccines and for ongoing monitoring of the manufacturing facilities where vaccines are produced. After FDA approval, safety is monitored using a multilayered system that includes the Vaccine Adverse Event Reporting System (VAERS), the Vaccine Safety Datalink (VSD) system, the Clinical Immunization Safety Assessment (CISA) Project, and periodic reviews by the National Academy of Medicine (NAM), previously the Institute of Medicine. In addition, there is a large number of studies published each year by the nation’s—and world’s—medical research community on vaccine effectiveness and safety.
Continue to: VAERS