The outbreaks of mumps* in Kansas and 10 other states, and measles in Boston, prompt us to question how well we in the United States are protected against infectious diseases thought to be adequately controlled, if not completely eradicated. Health providers are diligent in following Centers for Disease Control and Prevention and state and city health department recommendations for childhood immunizations; children are required to show proof of vaccines in order to attend school. Health providers are not as diligent in following the recommended schedule of immunizations for adults. The 2006 cases of mumps and measles occurred in adults, not children. A lesson learned is that presumption does not equal proof.
Vaccine Failure
Susceptibility is the result of primary or secondary vaccine failure. Primary vaccine failure (PVF) occurs when an individual does not make detectable antibodies in response to a vaccine. Secondary vaccine failure (SVF) occurs when an individual initially makes detectable antibodies in response to a vaccine, but then titers fall over time and render the individual nonimmune once again. Possible explanations for PVF include: 1) the ability of individuals to file a religious exemption thus producing a subset of the population that never receives vaccines; 2) individuals with medical contraindications, who may not be adequately immunized; 3) the failure of many children and adults to initially present to healthcare providers for primary series of vaccinations; and 4) administration errors due to improper storage of vaccines, inappropriate timing (for example, age or combining vaccines), and receipt of less effective vaccine preparations years ago. Secondary vaccine failure can be linked to failure to receive boosters as per schedule and even insufficient information about length of immunity at the time of initial introduction and use of a new vaccine.
Immunity Controversy
Because individual immune response to an antigen varies, laboratory methods can fail to detect antibodies in individuals who are actually immune. This dilemma creates differing opinions between practitioners and infectious disease specialists on the definition of immunity. New vaccines are on the horizon-a recent approval is a vaccine to prevent human papilloma virus infection. Ambitious efforts and resources are currently being invested in the development of a vaccine against human avian flu. New vaccines are often blurred by controversies over efficacy versus safety.
Another question in the debate over vaccines: Are we crippling the immune systems of our children with vaccines, especially in light of the fact that the presumption of acquired immunity is not without doubt? Individuals will still remain susceptible. Are there benefits to allowing natural immunity (for viral diseases) to evolve again?
Different groups are identified as high risk for different vaccine-preventable diseases, and immunization efforts are targeted at these populations, such as vaccination against bacterial meningitis for college freshman students living in dormitories. We are a global society and international travel has significantly increased exposure and potential for susceptible individuals to become infected in areas of the world where highly contagious diseases are still endemic. The calm of "control" is disrupted with an outbreak. Nurse practitioner education and training prepare us to be proactive and regularly assess preventive healthcare needs of patients.
Jamesetta Newland, PhD, APRN, BC, FNP, FAANP, FNAP
Editor-in-Chief
[email protected]
*On June 1, 2006, the Advisory Committee on Immunization Practices published revised recommendations for the control and elimination of mumps. [Context Link]