Vaccine issues: a commentary

September 2004

In this issue of Infectious Disease News are five articles and an editorial by Bill Schaffner, MD, all of which deal with vaccines. Some of the vaccines discussed are often considered more as pediatric vaccines; with each of these vaccines, however, there are implications for adults and adult immunization that are well worth discussing in these pages.

Varicella and hepatitis A

Marie Rosenthal’s article on varicella highlights the issue of “breakthrough” cases that are being seen in previously immunized children. This is somewhat analogous to the “breakthrough” cases of measles that previously occurred and because of which a second dose of measles vaccine has now become standard. The same solution seems likely to be implemented with varicella vaccine (Varivax, Merck). Of greater interest, perhaps, to infectious disease physicians is the possible prevention of herpes zoster by varicella immunization of adults. This issue is under active study at this time, and results should be available in 2005.

Judith Rusk’s article on hepatitis A vaccine raises a slightly different issue, that of targeted immunization vs. universal use. Recall that when hepatitis B vaccine was released, the initial thrust was targeted immunization directed at population subgroups that had an increased risk of exposure to hepatitis B, eg injecting drug users, men who have sex with men, individuals with multiple sex partners, prisoners and health care personnel. When that approach failed to make a significant dent in the number of cases of hepatitis B, the next strategy was immunization of children as they entered puberty. When that approach failed as well, the last step was universal immunization of infants, an approach that finally seems to be working. The whole cycle took 10 to 15 years. History seems to be repeating itself now with hepatitis A vaccine, and in a comparable time frame as well. Universal hepatitis A immunization of children is a likely Advisory Committee on Immunization Practices (ACIP) recommendation within the next several years. This was, in fact, predicted by several observers shortly after hepatitis A vaccine was released.

Vaccines awaiting approval

A pertussis booster immunization for adolescents and young adults has been an obvious need for decades. Development of acellular pertussis vaccines has finally resolved the safety issues for older populations, and the only remaining question is when this will finally be approved. There is ample documentation of the frequency and the reservoir of pertussis in adults, especially young adults. Health care personnel especially are candidates for this booster. The populations for which booster doses are recommended, the frequency of boostering and the like remain to be resolved by the ACIP and other organizations such as the IDSA/American College of Physicians immunization committee. For example, should there be a Tdap (tetanus toxoid, adult dose of diphtheria toxoid, and acellular pertussis) product that is routinely used for all adult boosters? Should that product also be used in emergency departments when a tetanus booster is indicated in wound management?

The expected approval of a quadrivalent meningococcal conjugate vaccine will also raise some interesting issues. Partly because of waning immunity and partly because the disease was so infrequent, the current polysaccharide vaccine has been recommended only for epidemic control and in populations that could be shown to be at increased risk. In the United States, these populations are primarily military recruits and college students. Will the new conjugate vaccine change the thinking of the ACIP? I’ll predict the recommendations will stay largely the same, although the definition of “increased risk” may be somewhat expanded. Cost-benefit considerations will likely mitigate against a recommendation for universal use.

Flu vaccine for health care personnel

The remaining two articles deal with influenza vaccine, which regular readers will recognize as one of my favorite topics. One article describes the changing recommendation for use in all children. Dr. Schaffner’s editorial (click here to read article) describes further the recommendations of the National Foundation for Infectious Diseases (NFID) and the fact that we really do need to improve on the half-hearted immunization programs in health care facilities. The NFID document, available at its Web site (www.nfid.org), should be read by all interested readers, and certainly by all Society for Healthcare Epidemiology of America members. The underlying rationale in this effort is patient safety, pure and simple. We (health care personnel) are transmitting influenza to our patients every year, and we have failed to recognize and to act to prevent that.

To be sure, some health care personnel should receive influenza vaccine to protect themselves, and in the event of a brand-new pandemic strain, there will be considerable interest in vaccine among health care personnel. That aside, however, there is no longer a credible excuse for not achieving a vaccination rate of 80% or more among health care personnel. Patient safety demands it!