ATLANTA – No changes are being made to the current recommendation of herpes zoster vaccination for adults aged 60 years and older, the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices reported at its June meeting.
The Food and Drug Administration licensed the herpes zoster vaccine (Zostavax) for use in adults aged 50-59 years in March 2011, said Dr. Paul Cieslak, chair of the zoster working group. However, the working group does not currently propose changes to the current recommendations.
Data from studies conducted by Merck, the maker of Zostavax, have shown vaccine efficacy in the 50-59 age group, but there is insufficient evidence regarding the duration of vaccine protection when it is given well before the peak age for zoster incidence, Dr. Cieslak noted.
Also, "it might be inappropriate to expand recommendations while the vaccine remains in short supply," he said, adding that the incidence could increase "if limited supply is used at time of low incidence." He also pointed out, however, that "the decision of the working group at this time is not intended to prejudice future deliberations."
ACIP currently recommends the herpes zoster vaccine (HZV) for all adults aged 60 years and older with no contraindications and for adults older than 80 years with chronic illnesses.
James Robinson, vice president of vaccine product and technology operations at Merck, spoke to the committee about the company’s plans to address production issues that limited the vaccine supply in recent years. According to Mr. Robinson, Merck distributed 2 million doses of zoster vaccine in the first 7 months of 2011 and expects to distribute another 2 million doses between July and December 2011, which approximately doubles the production from previous years.
New Study Results: Duration of Protection
ACIP’s research, however, suggests that more data are needed before a vote is reconsidered. The duration of the vaccine’s protection in younger adults is a key unknown factor, as is the cost effectiveness, said Dr. Rafael Harpaz of the CDC.
Dr. Harpaz presented data that showed protection of 3-4 years after zoster vaccination and possibly a few years longer. "What we don’t know: Will HZV protect 15 years or 30 years when it really counts?" he asked. Government data estimate that the average 50-year-old man in the United States can expect to live another 29 years, and the average 50-year-old woman can expect to live another 32 years, so there would be a substantial excess of zoster in older adults if a limited supply were diverted to younger adults, he noted.
Studies of the cost effectiveness of the zoster vaccine show a J-shaped curve. "Among adults aged 60 years and older, cost effectiveness of HZV is less favorable at the youngest and oldest ages of that range," Dr. Harpaz said. Cost effectiveness is reduced at younger ages because the protection is likely to wane by the time the recipient reaches the age when the disease burden of herpes zoster is highest. Cost effectiveness is also reduced in the elderly because of death and the decline in vaccine effectiveness over time.
Dr. Harpaz also addressed past supply shortages. Expanding recommendations before sustainable supplies are assured "can jeopardize the credibility of all players in the vaccine enterprise," he said. "ACIP has never adopted an expansion of a vaccination program in the midst of a supply shortage."
Other factors that prompted ACIP to refrain from recommending the zoster vaccine for adults aged 50-59 years include price, storage and handling issues, and complicated relationships of drug plans with pharmacies, he said.
The next steps include a Notice to Readers from the CDC that will appear on the CDC herpes zoster website to alert health care providers and the public to the change in licensure for the zoster vaccine and to emphasize that the ACIP recommendations have not changed.
The zoster working group recognized that some providers might wish to use the zoster vaccine for some patients aged 50-59 years, said Dr. Harpaz. The working group suggested that the CDC provide limited technical guidance for nonrecommended use in these patients, based on the current ACIP recommendations for adults aged 60 years and older.
Neither Dr. Cieslak nor Dr. Harpaz had any relevant financial conflicts to disclose.