Adverse Events following Japanese Encephalitis Vaccine
The Vaccines
Three types of Japanese Encephalitis (JE) vaccines are currently in
large-scale production and use in the world:
Mouse brain-derived inactivated vaccine is produced in several
Asian countries, China -province of Taiwan-, India, Japan, Korea,
Thailand and Vietnam (WHO, 1994). It is inactivated by formaldehyde, and
contains gelatin as a stabilizer and thiomersal as a preservative.
Cell culture-derived inactivated vaccine: primary hamster kidney
cells are used in China
Cell culture-derived live attenuated SA14-14-2 vaccine is based
on a stable neuro-attenuated strain of JE virus prepared in China
Mild adverse events
Mouse brain-derived inactivated vaccine
Local reactions such as tenderness and swelling occur in about 20% of
the vaccine recipients. A similar percentage may experience mild
systemic symptoms including headache, low-grade fever, myalgia, malaise
and gastrointestinal symptoms are reported 10 to 30% of vaccine
recipients (Poland et al., 1990; WHO, 1998).
Cell culture-derived inactivated vaccine
Local reactions, including swelling at the injection site are
observed in about 4% of vaccine recipientses, and mild systemic
symptoms, such as headache and dizziness are reported by fewer than 1%
of vaccine recipients.
Cell culture-derived live attenuated vaccine
Clinical monitoring of experimentally immunized subjects has
documented the absence of local or systemic symptoms In a study of 867
children in whom fever was monitored over a 21-day period after
immunization, temperatures above 37.6°C were recorded in less than 0.5%
of vaccine recipients (Yu et al, 1988).
Severe adverse events
Mouse brain-derived inactivated vaccine:
The manufacturing process purifies the infected mouse brain
suspension extensively, and myelin basic protein content is controlled
below 2 ng per ml. Vaccine related neurological complications were not
observed more often in vaccine recipients than in control groups in the
Japanese studies from 1955-66. However, since 1992, several cases of
acute encephalitis temporally linked to JE vaccination have been
reported. From the Republic of Korea, 3 such cases were recently
reported, of which 2 were fatal.
Hypersensitivity reactions, serious generalized urticaria, facial
angio-oedema or respiratory distress have been observed in adult Western
vaccine recipients (Anderson & Ronne, 1991; Plesner & Ronne, 1997; Ruff
et al., 1991; CDC, 1993). The frequency of these reactions ranges
between 1 and 64 per 10,000 vaccine recipients (Tsai & Chang, 1999).
Although not clearly explained, these reactions may be in connection
with gelatin, used as a stabilizer.
Cell culture-derived inactivated vaccine.
Fever higher than 38°C was previously a complication in 12% of the
vaccine recipients, but after a reduction of bovine serum in the
currently fomulated vaccine, febrile convulsions have halved. An
urticarian allergic reaction was observed in 1 of nearly 15,000 vaccine
recipients surveyed (Tsai & Chang, 1999).
Cell culture-derived live attenuated vaccine
A block randomized cohort study of 13,266 vaccinated and 12,951
non-vaccinated 1- to 2-year-old children followed prospectively for 30
days confirmed the vaccine safety. No cases of encephalitis or
meningitis were detected in either group, and rates of hospitalization
were similar in the two groups. The observations excluded a
vaccination-related encephalitis risk above 1 in 3400 (Liu et al, 1997).
As a precaution, vaccine recipients should be observed for 30 minutes
after vaccination. Epinephrine and other medications and equipment to
treat anaphylaxis should be available. Vaccine recipients should be
warned about the possibility of delayed urticaria and angioedema of the
head and the respiratory track and advised to remain in areas with ready
access to medical care in the 10 days after receiving a dose of JE
vaccine.
References
Anderson MM, Ronne T. Side Effects with
Japanese Encephalitis Vaccine. Lancet 1991, 337: 1044.
Centers for Disease Control and Prevention. Inactivated Japanese
Encephalitis Virus Vaccine: Recommendations of the Immunization
Practices Advisory Committee (ACIP). MMWR 1993; 42(No.RR-1):
1-15.
Liu ZL, Hennessy S, Strom BL, et al. Short term safety of attenuated
Japanese encephalitis vaccine (SA14-14-2): results of a randomised trial
with 26,239 subjects. J Infect Dis 1997; 176: 1366-9.
Plesner AM, Ronne T. Allergic mucocutaneous reactions to Japanese
encephalitis vaccine. Vaccine 1997;15: 1239-43.
Poland JD, Cropp CB, Craven RB, et al. Evaluation of the potency and
safety of inactivated Japanese encephalitis vaccine in US inhabitants.
J Infect Dis 1990;161:878-82.
Ruff TA, Eisen D, Fuller A et al. Adverse reactions to Japanese
encephalitis vaccine. Lancet 1991;338:881-2.
Tsai TF, Chang GJJ, Yu YX. Japanese Encephalitis Vaccines. In Plotkin
SA, Orenstein WA, eds. (1999). Vaccines (3rd ed.).
Philadelphia, PA: WB Saunders Company, pp 672-710.
Vaughan DW, Hoke CH. The epidemiology of Japanese Encephalitis :
Prospects for Prevention. Epidemiol Rev 1992; 14: 197-221.
WHO. Japanese encephalitis vaccines: WHO position paper. Wkly
Epidemiol Rec 1998; 73: 337-44.
WHO. Japanese encephalitis. Inactivated Japanese encephalitis virus
vaccine. Wkly Epidemiol Rec 1994; 69: 113-8.
Yu YX, Ming AG, Pen GY, et al. Safety of a live attenuated Japanese
encephalitis virus vaccine (SA14-14-2) for children. Am J Trop Med
Hyg 1988; 39:214-7.
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