CHICKEN POX VACCINE EDITORIAL

[Guest guest]

Debbie LT Bermudes wrote:

Subjects: Chickenpox vaccine - Administration and dosage

The American Academy of Pediatrics has issued recommendations for the

use of live attenuated varicella vaccine.[1] The article[2] that

introduces the AAP recommendations provides a well-written, clear review

of issues related to the varicella vaccine. The AAP recommendations

include the following:

1. A single dose of varicella vaccine for all healthy children ages 12

to 18 months who lack a reliable history of varicella.

2. A single dose of vaccine for children between 18 months and 13 years

of age who have not been previously immunized and who lack a reliable

history of varicella.

3. Two immunizations four to eight weeks apart after the 13th birthday

for children without a history of varicella.

The AAP recommendations are comparable to the AAFP recommendations for

the varicella immunization. Specific recommendations for adults are not

provided in the AAP clinical policy Varicella vaccine may be

simultaneously given with the measles-mumps-rubella (MMR) vaccine but

separate syringes and separate injection sites must be used. If the

injections are not given simultaneously, the varicella vaccine and the

MMR vaccine should be administered at least one month apart.

Disappointing in the AAP policy is the relatively weak literature

review. Although the data strongly suggest that the varicella vaccine is

effective, the policy cites only four published studies dealing with

children,[3-6] two of which are at least 10 years old. According to

unpublished data from the manufacturer, the vaccine is approximately 70

percent effective against the disease after household exposure and is 95

percent effective in lessening the severity of disease.

Other data show that the rate of varicella after immunization during

eight years of study was less than 1 to 3 percent per year, compared

with the annual varicella rate of 7 to 8 percent in unvaccinated

children. No waning immunity in children was demonstrated. To its

credit, the policy includes a discussion of the financial impact

of immunization. According to several published cost-effectiveness

analyses, the vaccine most likely saves money when looked at from a

broad perspective (i.e., when including such economic costs as parental

time off work).

The clinical policy is disappointing, however, in its lack of

explicitness. Authorship and the methods used for compilation of

evidence, for example, are not clear. Likewise, policy recommendations

are not flexible (i.e., they do not allow variation based on patient

preferences or needs). Given that varicella is a predominantly benign,

self-limited disease of childhood and given that the long-term effects

of immunization are not clear, such flexibility would have been

appropriate. Fortunately, adverse events after vaccination are minimal.

Only about 7 to 8 percent of those vaccinated develop a mild

vaccine-associated rash, with an average of two to five lesions.

Since vaccine virus has been recovered from these lesions, appropriate

precautions should be taken for potential contacts who are susceptible

to the infection. There are a few cases in which contacts have

contracted vaccine-induced disease. Illness in these contacts has been

subclinical or extremely mild, which indicates that the vaccine virus

remains attenuated when transmitted. Unpublished data from the

manufacturer demonstrated that immunization of 985 individuals already

immune to varicella did not result in a significant increase in the

adverse effect profile. One concern associated with the immunization

is the potential for zoster-like illness to occur either with

immunization or later in life. The incidence of zoster-like illness with

the vaccine approximates that of the natural infection. Based on 13

years of follow-up in the United States, the

varicella vaccine does not appear to be accompanied by an increase in

the incidence of

zoster infection in adults[7] (although it is too early to offer any

definite observations).

Storage specifications for the vaccine may limit its use in general

family practice. Because the vaccine must be stored at -15[degrees] C

(5[degrees] F) or colder, family physicians must be aware of the storage

temperature of their office freezers. Since the vaccine must be used

within 30 minutes once it has been constituted, administering the

vaccine without special arrangements can be difficult. In addition, the

vaccine must not be administered to immunocompromised individuals or to

people living in households with potential immunocompromised contacts,

children receiving steroids, those with acute lymphocytic leukemia and

women who are pregnant or lactating. Since the vaccine includes

neomycin, it should not be administered to individuals who have had an

anaphylactic reaction to neomycin. Whether Reye syndrome results from

salicylate administration after varicella vaccination is not known, but

the manufacturer recommends that salicylates not be administered for six

weeks after administration of the vaccine.

Dr. Ganiats is associate professor and vice-chair of the Department of

Family and Preventive Medicine at the University of California-San Diego

School of Medicine. He is a member of the AAFP Task Force on Clinical

Policies for Patient Care.

REFERENCES

[1.] AAP recommends use of live attenuated varicella vaccine [special

Medical Reports). Am Fam Physician 1995;52:1922,1924-27.

[2.] American Academy of Pediatrics Committee on Infectious Diseases.

Recommendations for the use of live attenuated varicella vaccine.

Pediatrics 1995;95:791-6.

[3.] Kuter BJ, Weibel RE, Guess HA, s H, Morton DH, Neff BJ, et

al. Oka/Merck varicella vaccine in healthy children: final report of a

2-year efficacy study and 7-year follow-up studies. Vaccine

1991;9:643-7.

[4.] Asano Y, Nagai T, Miyata T, Yazaki T, Ito S, Yamanishi K, et al.

Long-term protective immunity of recipients of the Oka strain of live

varicella vaccine. Pediatrics 1985;75:667-71.

[5.] Weibel RE, Neff BJ, Kuter BJ, Guess HA, Rothenberger CA, Fitzgerald

AJ, et al. Live attenuated varicella vaccine. Efficacy trial in

children. N Engl J Med 1984;310:1409-15.

[6.] BM, Piercy SA, Plotkin SA, Starr SE. Modified chickenpox in

children immunized with the Oka/Merck varicella vaccine. Pediatrics

1993; 91:17-22.

[7.] Hammerschlag MR, Gershon AA, Steinberg SP, e L, Gelb LD.

Herpes zoster in an adult recipient of live attenuated varicella

vaccine. J Infect Dis 1989; 160:535-7

[Published erratum appears in J Infect Dis 1989;160:1095!.

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