What You Need to Know About the ACIP’s Recommendations on Herpes Zoster Vaccination

The CDC's Advisory Committee on Immunization Practices (ACIP) recommends that all persons older than 60 years be immunized against the varicella-zoster virus that causes herpes zoster with a single dose of the live, attenuated virus vaccine Zostavax (Merck & Co, Inc, Whitehouse Station, NJ). Furthermore, it urges clinicians to offer the vaccine on the first available clinical encounter.

The recommendations, which will appear in Morbidity and Mortality Weekly Report (MMWR), can be accessed online.¹ These recommendations are the first made by the ACIP advocating use of a live, attenuated virus vaccine for prevention of herpes zoster. The hope-promised by results of several clinical trials cited in the MMWR article-is that routine immunization of older adults will significantly ameliorate the incidence of and morbidity associated with herpes zoster.

About 1 million cases of herpes zoster are diagnosed annually in the United States. Many of them will be associated with postherpetic neuralgia (PHN), stated the ACIP, which summarized various other complications in its recommendations statement. Included are ocular symptoms and sequelae (ie, herpes zoster ophthalmicus); varicella-zoster virus viremia; and serious, potentially fatal neurological conditions and viral dissemination to viscera that can occur in persons who are immunocompromised. Older persons (beginning at about age 50) are particularly at risk for development of herpes zoster, with 2 studies calculating that 50% of persons who live to age 85 years will have experienced this condition and subsequent PHN.^2,3 T

The Vaccine and Vaccination

Each 0.65-mL dose of the zoster vaccine (when reconstituted and stored at room temperature for up to 30 minutes) contains a minimum of 19,400 plaque-forming units of the Oka/Merck strain of varicella-zoster virus. This vaccine is appreciably more potent than the varicella vaccine routinely used in children to prevent chickenpox (ie, Varivax, also manufactured by Merck & Co, Inc). It is administered subcutaneously to the deltoid area. Asingle dose is all that is required (booster doses are not licensed for use). 

Zoster vaccine should be stored in a freezer that maintains an average temperature of -15C (5F) or colder. Once reconstituted, the vaccine should be used immediately: within 30 minutes. After this time, the potency degrades. If unused, the reconstituted vaccine should be discarded.

The zoster vaccine is licensed for use only in persons 60 years and older. It is safe for use in persons receiving blood products. Persons who already have received immunization against varicella-zoster virus should not be re-immunized; however, the ACIP stated that concern regarding unintentional re-immunization in persons 40 years and older was slight because varicella vaccination did not begin in the United States until 1995. The ACIP also noted that clinicians need not question older patients about a history of chickenpox or conduct serological testing for varicella immunity before administering the vaccine. Persons who have had an episode of herpes zoster in the past can receive the vaccine, but it should not be used to treat acute herpes zoster or PHN or be used as prophylaxis against PHN. Precluding contraindications and precautions related to health status, persons with chronic renal failure, diabetes mellitus, rheumatoid arthritis, chronic pulmonary disease, or other chronic conditions can receive the vaccine.

Vaccine Coadministration

Although the zoster vaccine can be administered along with the trivalent inactivated influenza vaccine without compromising the effectiveness of either one, no data are available on the effects of administering the zoster vaccine with other vaccines that are routinely recommended for persons 60 years and older. Because simultaneous administration of most commonly used live, attenuated and inactivated vaccines, in general, has yet to be associated with impaired immune response and has not been associated with an increased rate of adverse events,⁴ the zoster vaccine can be administered in the setting of other indicated (inactivated) vaccines during the same office visit.

 The ACIP reminded clinicians that when multiple vaccines are to be administered during a single office visit, they should be administered to different anatomic sites using separate syringes. Although the zoster vaccine can be administered at any time along with an inactivated virus vaccine, it should be administered at least 4 weeks before or after administration of another live, attenuated virus vaccine.

Who Should Not Be Vaccinated

Because the risk of morbidity and mortality from herpes zoster is heightened in immunocompromised persons, eligible patients who are scheduled to begin immunosuppressive therapy should be immunized at least 14 days (and preferably a month, according to some experts⁵) before immunosuppressive therapy is initiated. Otherwise, immunization is contraindicated in immunocompromised persons, including those receiving immunosuppressive drugs. However, exceptions and caveats to these guidelines exist (Table). 

Table

Although a history of neomycinassociated contact dermatitis is not a contraindication to receiving the zoster vaccine, persons who have a history of anaphylactic reaction to any component of the vaccine, including neomycin, should not receive it.⁴ Pregnant women-who are not in the target age group for herpes zoster immunization anyway-also should not receive the vaccine. Clinicians should be aware that the CDC and the vaccine's manufacturer have established a registry to monitor maternal-fetal outcomes of pregnant women who inadvertently have been administered live, attenuated varicella-zoster virus-type vaccines within a month of becoming pregnant. The telephone number of the registry is 800-986-8999. 

Persons who are receiving an antiviral medication, such as acyclovir, famciclovir, or valacyclovir, should not be vaccinated in the setting of active therapy. Rather, therapy should be discontinued for at least 24 hours before the zoster vaccine is administered and at least 14 days should elapse postvaccination before antiviral therapy is resumed^.4 Because antiviral agents are active against herpesviruses, they could interfere with vaccine effectiveness.

Additional Notes and Caveats

Clinicians are asked to document all immunizations in the patient's medical record, per the ACIP's General Recommendations on Immunization, published in 2006.⁴ The type of vaccine, the vaccine's manufacturer, anatomic site and route of delivery, the date of vaccine administration, lot number of the vaccine, and name of the administering facility should be recorded. In addition, to help avoid inadvertent re-immunization, patients should be given a copy of the document containing a record of the vaccination.

If the zoster vaccine was inadvertently administered to a child, the ACIP recommends that the dose be counted as a single valid dose of varicella vaccine. If the erroneously administered dose of zoster vaccine was given instead of the first dose of varicella vaccine, a second dose of varicella vaccine is required. The ACIP has requested that such errors be reported to the Vaccine Adverse Event Reporting System (VAERS) whether or not an adverse event occurs.

Conversely, if a clinician mistakenly administers varicella vaccine to a person for whom the zoster vaccine was indicated, no specific safety concerns apply; however, the dose should be considered invalid, and the patient should immediately be given a dose of zoster vaccine. If a delay in recognition of the error occurs, the zoster vaccine should be promptly administered 28 days after the varicella vaccine was given.

As with other vaccines, clinically significant adverse events should be reported to VAERS even if a causal relation to vaccination is questionable. Clinicians are encouraged to enter reports electronically at https://secure.vaers.org/ VaersDataEntryintro.htm. The Web site of the VAERS is www. vaers.hhs.gov and the telephone number is 800-822-7967.

References:

•  Centers for Disease Control and Prevention. Prevention of herpes zoster. Recommendationsof the Advisory Committee on Immunization Practices (ACIP). www.cdc.gov/ mmwr/preview/mmwrhtml/rr57e0515a1. htm?s_cid=rr57e0515_e. Accessed June 10, 2008.

•  Brisson M, Edmunds WJ, Law B, et al. Epidemiology of varicella zoster virus infection inCanada and the United Kingdom. Epidemiol Infect. 2001;127:305-314.

•  Schmader K. Herpes zoster in older adults. Clin Infect Dis. 2001;32:1481-1486.

•  Centers for Disease Control and Prevention. General recommendations on immunizationof the Advisory Committee on Immunization Practices. MMWR. 2006;55(RR-15):1-48.

•  Ihara T, Kamiya H, Torigoe S, et al. Viremic phase in a leukemic child after live varicella vaccination. Pediatrics. 1992;89:147-149.