ATLANTA — Most internists and family physicians would recommend the herpes zoster vaccine to their older patients despite concerns about the vaccine's cost and reimbursement for its administration, Dr. Allison Kempe reported at a meeting of the Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention.
The findings came from a national survey of internists and family physicians conducted by Dr. Kempe and her associates at the University of Colorado, Denver, in November and December 2005.
The U.S. Food and Drug Administration is currently reviewing the licensure application for Zostavax, which was filed by Merck & Co. in April 2005. In June 2005, the vaccine received widespread media coverage with the publication of a study showing 51% efficacy in preventing herpes zoster, 66.5% efficacy against postherpetic neuralgia, and 61% reduction in pain in adults aged 60 and older (N. Engl. J. Med. 2005;352:2271–84).
Less than 10% of the surveyed physicians expressed concern about the fact that the vaccine must be kept frozen rather than refrigerated, yet previous experience with other live virus vaccines in primary care settings suggests this might be a bigger problem than many physicians realize, Dr. Gregory S. Wallace of the CDC told the advisory committee in a separate presentation.
Of the 270 general internists and 325 family physicians who participated in the survey (response rates of 62% and 76%, respectively), 35% “strongly” agreed that herpes zoster and postherpetic neuralgia cause significant burden among older patients, while another 46% “somewhat” agreed.
The percentage of physicians who strongly agreed that the burden of the two disorders was “sufficient enough to warrant a vaccine” was significantly higher with regard to patients aged 60–79 years, compared with patients aged 50–59 years (40% vs. 15% among internists and 29% vs. 17% among family physicians).
Overall, physicians of both specialties reported being somewhat or very likely to recommend the vaccine for all patients over 50 years, but were significantly more likely to recommend it to patients aged 60 and older than to those aged 50–59 (79% vs. 57% among internists and 78% vs. 60% among family physicians).
Despite their overall support for the vaccine, respondents did perceive several potential barriers to administering it. “Lack of reimbursement” topped the list, with 76% saying that would “definitely” be a barrier or would be “somewhat” of a barrier. “Patients unwilling to pay if not covered by insurance” and “up-front costs to purchase vaccine” were the second and third most important barriers, respectively.
In addition to the issue of freezer storage, other potential barriers cited by less than 10% of respondents included “concerns about safely administering a live attenuated virus to patients with chronic medical conditions,” and the “fact that vaccine will not be licensed for immunosuppressed patients.”
The low level of concern for those two issues appears justified: There were no major safety problems in the published study, in which 90% of the 38,546 subjects had at least one prior medical condition, including more than 20% each with arthritis and hypertension, Dr. Paula Annunziato of Merck told the committee.
Immunosuppressed individuals were excluded from the study, and none of the survey respondents had treated or referred any such patients for herpes zoster or postherpetic neuralgia in the previous year, Dr. Kempe said.
But freezer storage, which is required for all live virus vaccines, may indeed turn out to be a problem in many practices, according to the CDC's Dr. Wallace.
In one previous study of more than 700 primary care providers, 18% of freezers were being kept too warm for proper storage of varicella vaccine, measles-mumps-rubella-varicella vaccine, or live attenuated influenza vaccine (Flumist), all of which must be kept at or below 5° F (Am. J. Prev. Med. 2002;23:246–53). Another study of 221 private provider offices found that 17% of freezers were too warm (Pediatrics 2001;107:e100–4).
Recently, it has become apparent that the opposite is a problem, too: In order to keep the freezer cold enough for live virus vaccines, the refrigerator compartment may become too cold, which is damaging to inactivated vaccines that are stored there (MMWR 2003;52:1023–5). This is a particular problem in small dormitory-style refrigerators without a separate freezer section; these are unacceptable for storing vaccines, Dr. Wallace said.