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Varicella-Zoster Immune Globulin Distribution --
United States and Other Countries, 1981-1983
Since its licensure on February 1, 1981, varicella-zoster
immune
globulin (VZIG) has been produced and distributed in Massachusetts
by
the Massachusetts Public Health Biologic Laboratories (MPHBL) and
distributed elsewhere by the American Red Cross Services--Northeast
Region through regional blood centers (see pages 97-99). Before
licensure, VZIG was distributed as an investigational new drug
(IND),
first by CDC and later by CDC and the Sidney Farber Cancer
Institute.
Between February 1, 1981, and September 30, 1983, 27,641 vials of
VZIG
were distributed in the United States (24,190 vials), Canada
(1,987),
and 15 other countries (1,464). This represents between 9,000 and
10,000 exposures to varicella-zoster (V-Z) virus. During the IND
period of January 1, 1978, to November 30, 1980, 5,735 vials (for
2,263 exposures) were distributed using strict eligibility criteria
(1) (Table 1). (Data for December 1980 and January 1981 are
unavailable.) Distribution increased threefold during the first
year
after licensure, followed by a 67% increase in 1982. Data
available
through September 1983 suggest that the observed rate of increase
in
distribution between 1980 and 1982 has diminished substantially.
Seasonal distribution patterns of VZIG distribution and
reported
varicella occurrence are similar, with the peak period of
distribution
(February-May) coinciding with the expected varicella seasonal peak
incidence (2) (Figure 1). Based on annual averages, between three
(January) and 11 (August and September) times as much VZIG was
distributed as a licensed product than as an IND.
Since there was little basis for projecting the potential
demand
for VZIG as a licensed product, VZIG initially was released on a
case-by-case basis to ensure that the available supply was adequate
to
meet the most critical exposure situations (i.e., exposure
involving
susceptible, immunocompromised children). When it became evident
that
supplies were sufficient for all indicated applications, VZIG was
distributed for use as physicians deemed appropriate. Although
VZIG
was intended primarily for use in high-risk neonates and
susceptible
immunocompromised children 15 years of age or younger (1), some
physicians considered certain older individuals at increased risk
of
serious complications if infection occurred.
Although nationwide data on VZIG use in adults are not
available,
distribution of VZIG to adults in Massachusetts was evaluated by
the
MPHBL using information on the patients' underlying conditions,
types
of exposure, intervals between exposure and the VZIG request, and
likelihood of previous infection. Between February 1, 1981, and
September 30, 1983, 40 exposures were recorded among adults. These
accounted for 12% of the 321 Massachusetts VZIG requests and 19% of
the 1,028 vials distributed (five vials per adult exposure).
Overall
adult usage did not vary over this 3-year period. Age, which was
known for 29 individuals, ranged from 16 to 73 years, with a mean
and
median of 37.4 years and 32.0 years, respectively.
The most frequently recorded indications judged appropriate by
the
requesting physicians for VZIG use were immunosuppression
(secondary
to radiation or chemotherapy) and pregnancy (12 patients each)
(Table
2). Three of six pregnant women with known gestation were given
VZIG
in the first trimester. Twenty of the 32 known exposures occurred
in
households; two involved exposures of hospital personnel. The
interval between exposure and VZIG request was known for 23
requests;
three were beyond 96 hours (the recommended maximum interval
between
exposure and prophylaxis). One patient with Hodgkin's disease was
given VZIG 8 days after onset of zoster, which is not an indication
for VZIG use. Two additional requests were made within 1 week of
exposure. All patients had either negative or uncertain histories
of
previous varicella infection. Serologic testing was performed too
infrequently to provide meaningful results.
Varicella developed in two of 29 adults (20 exposed in
households)
with known outcomes. Both involved household exposures--one in a
parent of a child with varicella and one in a pregnant woman (VZIG
had
been administered 5 days and 2 days, respectively, after exposure).
Both infections were mild. The outcome of the pregnancy is
unknown.
The observed clinical attack rate following household exposure of
10%
(2/20) is lower than the expected 30%-50% rate in immunocompromised
children with a negative or uncertain history of previous varicella
(3,4), implying that many of these VZIG recipients were actually
immune.
Reported by J Leszczynski, DrPH, M McCabe, MPH, Massachusetts
Public
Health Biologic Laboratories, Jamaica Plain, PL Page, MD, American
Red
Cross Blood Services--Northeast Region, Needham, Massachusetts; Div
of
Immunization, Center for Prevention Svcs, CDC. Editorial Note
Editorial Note: As expected, VZIG licensure has led to a
substantial
increase in VZIG use. Although supplies seem adequate, use should
be
restricted to high-risk individuals who are likely to be
susceptible
and who have experienced significant exposures. VZIG is not
beneficial in cases of herpes zoster (5,6). Passive immunization
also
is not indicated for treating varicella (see page 96). It is not
known whether the adult VZIG requests for pregnant women in
Massachusetts were aimed at preventing maternal or fetal infection.
VZIG use has not been shown to protect the fetus from infection and
may provide a false sense of security. Decisions regarding VZIG
use
in pregnant women should be based on preventing serious illness in
the
mother, not on preventing infection in the fetus (1) (see page 95).
Finally, excessive use of VZIG can be minimized by realizing that
most
adults with negative histories of previous varicella are immune
(7-9).
Detailed recommendations for VZIG administration have recently
been published by the American Academy of Pediatrics (AAP) (10).
The
Immunization Practices Advisory Committee (ACIP) recommendations
are
published in this issue of the MMWR.
References
CDC. Varicella-zoster immune globulin--United States. MMWR
1981;30:15-6, 21-3.
Preblud SR, D'Angelo LJ. Chickenpox in the United States,
1972-1977. J Inf Dis 1979;140:257-60.
Orenstein WA, Heymann DL, Ellis RJ, et al. Prophylaxis of
varicella in high-risk children: dose-response effect of
zoster
immune globulin. J Pediatr 1981;98:368-73.
Zaia JA, Levin MJ, Preblud SR, et al. Evaluation of
varicella-zoster immune globulin: protection of
immunosuppressed
children after household exposure to varicella. J Infect Dis
1983;147:737-43.
Groth KE, McCullough J, Marker SC, et al. Evaluation of zoster
immune plasma. Treatment of cutaneous disseminated zoster in
immunocompromised patients. JAMA 1978;239:1877-9.
Stevens DA, Merigan TC. Zoster immune globulin prophylaxis of
disseminated zoster in compromised hosts. A randomized trial.
Arch Intern Med 1980;140:52-4.
Ross AH. Modification of chicken pox in family contacts by
administration of gamma globulin. N Engl J Med
1962;267:369-76.
Myers MG, Rasley DA, Hierholzer WJ. Hospital infection control
for varicella zoster virus infection. Pediatrics
1982;70:199-202.
Steele RW, Coleman MA, Fiser M, Bradsher RW. Varicella zoster
in
hospital personnel: skin test reactivity to monitor
susceptibility. Pediatrics 1982;70:604-8.
Committee on Infectious Diseases. Expanded guidelines for use
of
varicella-zoster immune globulin. Pediatrics 1983;72:886-9.
Disclaimer
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