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Thread: Japanese Encephalitis Vaccine - SCI Nurse please advise

  1. #1

    Japanese Encephalitis Vaccine - SCI Nurse please advise

    My daughter's Japanese Encephalitis Vaccine is due now. We live in Sri Lanka and usually this vaccine is given between one and two years. Earlier the vaccine was imported from Japan but this year the vaccine has been imported from Korea. Some friends told me that there might be side effects from this vaccine and not to give it. SCI Nurse please advise me. Are there any side effects if this vaccine is given.

  2. #2
    I am not familiar with this vaccine as it is not given in the USA. Here is the information about it from the CDC, but it does not address vaccine suppliers.

    Knowing the possible serious effects of any type of encephalitis, my inclination would be to get it. I would want to see scientific evidence and not just rumor that the Korean vaccine is dangerous for some reason.


  3. #3

  4. #4
    Japanese encephalitis is a viral infection that is spread by mosquitos. It is endemic in East and South Asia (see map below). The vaccine is highly recommended for children in affected areas. The following is what the CDC has to say about the vaccine and side-effects. Summarizing:
    • The original vaccine, as you point out, is from Japan. It is one of the oldest vacines, developed in 1954 from a virus isolated in 1935. Called the Biken vaccine, it is derived from infected mouse brains and contains thimerosal as a deriviative. Please note that thimerosal is controversial in the United States and has been claimed to be a cause of autism but many experts do not believe that his is true.
    • The vaccine has 80% efficacy. Field tests of the two dose vaccination in 1960's in Taiwan revealed 4 cases of the Japanese encephalitis (JE) amongst 100,000 vaccinated children, compared to 18 cases amongst 100,000 children vaccinated with placebo tetanus toxin. One dose had no efficacy. Three doses over 30 days appear to be most effective and antibody levels remain elevated for up to 3 years after a booster dose.
    • Side-effects of the vaccination include the usual local swelling and tenderness in about 20% of patients. About 10% of the patients get mild systemic signs, including fever, nausea, vomiting. Rarely, about 1-2 cases per million vaccinations, get neurological side-effects In the United States and Eruope, some cases of rashes have been reported with the vaccine. Note that these may well be reactions of components of the vaccine.
    • People who have proven or suspected hypersensitivity to proteins of rodents or neural origins, particularly a previous history of hypersensitivity to vaccines, should not receive the vaccine. A small study of patients with abnormal immune system showed that the vaccine is still effective. Deleterious interactions with other vaccines are rare or not known.

    An inactivated JE vaccine derived from infected mouse brain has been licensed in Japan since 1954 (24). JE vaccine licensed in the United States is produced by the Research Institute of Osaka University (Biken) and is distributed by Connaught Laboratories Inc. The Biken vaccine is the most widely used JE vaccine of its type.

    Similar mouse brain derived JE vaccines are produced by other manufacturers in India, Japan, Korea, Taiwan, Thailand, and Vietnam (25,26). In the PRC, inactivated and attenuated JE vaccines are produced in primary hamster kidney cells (27,28).

    The Biken vaccine is prepared with the Nakayama-NIH strain of JE virus, originally isolated in 1935 from an infected human. The vaccine is produced from infected mouse brains by a sequence of protamine sulfate treatment, formalin inactivation, ultra-filtration, and ammonium sulfate precipitation. The vaccine is purified further by ultracentrifugation through a sucrose cushion. Gelatin is added as a stabilizer during several steps of the process. No myelin basic protein (MBP) can be detected in the vaccine at a level of 2 ng/mL, the detection threshold of the MBP assay. Thimerosal is added as a preservative. Vaccine potency is determined in comparison with a reference vaccine of known clinical efficacy.


    Efficacy was demonstrated in a single placebo-controlled trial conducted in Thailand (13). The study compared the efficacy of two doses of monovalent JE vaccine prepared with the Nakayama-NIH strain (21,628 children) with two doses of a bivalent vaccine also containing the Beijing strain (22,080 children); 21,516 children were administered tetanus toxoid (TT) as a placebo. After 2 years, two JE cases were reported among recipients of either JE vaccine and 11 cases were observed in the placebo cohort, for an overall vaccine efficacy of 91% (95% confidence interval {CI} of 70%-97%). The monovalent and bivalent vaccines did not differ in their efficacy.

    A prototype of the currently licensed vaccine, which was a less refined mouse brain-derived product, was field tested in Taiwan in 1965 (29). Two doses of JE vaccine or TT were administered under masked protocol to 111,749 and 131,865 children, respectively; 22,194 children were administered a single dose of JE vaccine and 140,514 unvaccinated children also were observed. Observations during a single year showed rates of 4 per 100,000 in recipients of two JE vaccine doses and 18 per 100,000 in recipients of TT for a vaccine efficacy of 80%. A single vaccine dose had no demonstrable efficacy.


    Levels of neutralizing antibody that are considered protective have been defined by animal challenge experiments (24). A neutralizing antibody titer of greater than or equal to 1:10 in passively immunized mice protected against challenge with 105 LD(50) of JE virus, a viral dose that might be transmitted by an infected mosquito. Thus neutralizing antibody titers greater than or equal to 1:10 (as determined by the technique used at Biken) have been presumed to protect against natural infection.

    The dosage regimen shown to be efficacious in the trials cited previously, which is used for primary vaccination in many areas of Asia, consists of two doses administered 1-4 weeks apart. However, immunogenicity studies in the United States and among British subjects indicate that three doses are needed to provide protective levels of neutralizing antibody in a suitable proportion of vaccinees (Table 3) (17,30). Fewer than 80% of vaccinees receiving two doses seroconverted (reciprocal neutralizing antibody titer of greater than or equal to 8-10). Moreover, after 6-12 months, only 29% of vaccinees still had adequate antibody levels (17). The vaccine's efficacy and immunogenicity after two doses in Asian subjects may reflect the effects of prior immunity or subsequent exposures to JE, West Nile, dengue, and other flaviviruses circulating in Asia (31). Although exposure to flaviviruses is almost universal at an early age in developing areas of Asia, flaviviral infections are rare in North America and in most areas of Europe.

    Immunogenicity studies with another flaviviral vaccine (inactivated tick-borne encephalitis {TBE} vaccine) showed that previous flaviviral infections or yellow fever immunization augmented and accelerated the antibody response to TBE vaccine (32). Preliminary studies do not indicate such an effect among JE vaccine recipients (DeFraites R, unpublished data).

    The vaccine was more immunogenic when administered in three doses during a 30-day period (days 0, 7, and 30) than during a shorter period of 2 weeks (days 0, 7, and 14) (Table 3). Although all subjects seroconverted with either regimen, at 6 months geometric mean titers (GMT) were higher with the longer schedule (p<.0001) (DeFraites R, unpublished data).

    The longevity of neutralizing antibody after primary vaccination is not known. The GMT of vaccinees receiving three doses was unchanged between 6 months and 1 year (1:76) after the primary series. After a booster dose was administered at 1 year, neutralizing antibody titers increased sharply 3 months later to a mean titer of 1:1,117 (DeFraites R, unpublished data). Twenty-one subjects who did not receive a booster retained elevated antibody titers for 2 years after primary vaccination (GMT 1:105). Additional data on the persistence of antibody are pending. In one Japanese study, antibody titers above 1:10 persisted for 3 years after a booster dose (33).


    JE vaccination is associated with a moderate frequency of local and mild systemic side effects (13,17,25,26,34,35) (DeFraites R, unpublished data). Tenderness, redness, swelling, and other local effects have been reported in about 20% of vaccinees (less than 1%-31%). Systemic side effects -- fever, headache, malaise, rash, and other reactions such as chills, dizziness, myalgia, nausea, vomiting, and abdominal pain -- have been reported in about 10% of vaccinees.

    The neural tissue substrate of the vaccine has raised concerns about the possibility of vaccine-related neurologic side effects (36). The amount of mouse MBP in the vaccine, if any, is well below levels associated with an encephalitogenic effect in a guinea pig model. Surveillance of JE vaccine-related complications in Japan during the years 1965-1973, disclosed neurologic events (principally, encephalitis, encephalopathy, seizures, and peripheral neuropathy) among 1 to 2.3 per million vaccinees (37) (Biken, foundation for vaccination research, unpublished data). One case of Guillain Barre syndrome temporally related to JE vaccination has been reported in the United States since 1984; however, this patient also had pharyngitis 3 weeks before the onset of weakness and had a positive monospot test (DeFraites R, unpublished data). A causal relation between JE vaccination and temporally related neurologic events has not been established in this or other cases.

    Since 1989, an apparently new pattern of adverse reactions has been reported, principally among travelers vaccinated in Australia, Europe, and North America (35,38-39)(Navy Environmental Health Center, unpublished data; Cambridge Self Diagnostic Services, unpublished data; and Andersen MM, Rone T, personal communication) (Table 4). The reactions have been characterized by urticaria, often in a generalized distribution, and/or angioedema of the extremities, face, and oropharynx, especially of the lips. Three vaccine recipients developed respiratory distress. Distress or collapse because of hypotension or other causes led to hospitalization for several persons. Most reactions were treated successfully with antihistamines or oral steroids; however some patients were hospitalized for parenteral steroid therapy. Three patients developed associated erythema multiforme or erythema nodosum, and some patients have had joint swelling. Some vaccinees have complained of generalized itching without objective evidence of a rash. The immunologic mechanism of these adverse events has not been defined. Additional immunologic studies are pending.

    An important feature of these reactions has been the interval between vaccination and onset of symptoms. Reactions after a first vaccine dose occurred after a median of 12 hours following vaccination (88% of reactions occurred within 3 days). The interval between administration of a second dose and onset of symptoms generally was longer (median 3 days) and possibly as long as 2 weeks. Reactions have occurred after a second or third dose, when preceding doses were received uneventfully. Although some observers have reported that reactions occur chiefly after a second or third dose, one prospective study found similar reaction rates after first and second doses (Navy Environmental Health Center, unpublished data).

    A case-control study among U.S. military personnel found an association between reactions to JE vaccine and a past history of urticaria (after hymenoptera envenomation, medications, physical or other provocations or of idiopathic cause {relative risk 9.1, 95% CI 1.8-50.9}) (Navy Environmental Health Center, unpublished data).

    Surveillance of adverse reactions during a mass immunization campaign of 35,000 active duty U.S. military personnel and their dependents on Okinawa disclosed the sudden death of a 21-year-old man who had received a first dose of JE vaccine 60 hours earlier. He also had received a third dose of plague vaccine on the day of death. The man had a medical history of recurrent hypersensitivity phenomena and an episode of possible anaphylaxis. He reported no antecedent symptoms before he was found dead, and the cause of death was not established at autopsy.

    The incidence of these adverse reactions has varied widely depending on the circumstances of vaccine administration and surveillance (Table 4). In two reports from travelers' clinics in Australia and Canada, rates of 50-104 per 10,000 vaccinees were reported. National surveillance estimates in Denmark, Australia, the United Kingdom, and Sweden are about 10-fold lower and range from 0.7 to 12 per 10,000. Studies among U.S. citizens have disclosed rates of 15-62 per 10,000 (Table 4).

    Whether this pattern of adverse reactions is new for JE vaccine is unclear. Data from Denmark and Australia suggest that this may be the case. From 1983 to November 1989, no such adverse reactions were reported to the Danish State Serum Institute among recipients of 161,000 doses. From November, 1989 to June 1991, 19 cases were reported among 62,000 vaccine recipients (p less than 10-6, Poisson) (38). Although JE vaccine had been distributed to 4,000 persons in Australia since 1987, the seven adverse reactions meeting the above description were reported only after June 1990 (38). Other patients with similar clinical features were reported from the United Kingdom in 1991, from Canada in 1990, and Sweden in the period from 1989-1990. However, in retrospect, similar adverse events were observed in a JE vaccine trial conducted from 1983 to 1987 in the United States (17). One patient had an anaphylactic reaction occurring within 5 minutes of vaccination; the other subject developed generalized urticaria 7 hours after vaccination. Although the latter case initially was diagnosed as exercise-induced urticaria, a relation of the reaction to JE vaccine cannot be excluded.

    The vaccine constituent(s) responsible for these adverse events has (have) not been identified. Twelve of 45 vaccine lots produced from April 1988 to January 1991 have been associated with this pattern of adverse reactions. However, 26 of the remaining 33 lots were distributed exclusively to Asian countries. The absence of similar reports associated with these lots may be related to differences in the sensitivity of surveillance for adverse reactions, variations in susceptibility of vaccinees in Asia, or other lot variations. Therefore, whether the reactogenicity of JE vaccine produced recently is associated only with certain lots, or whether a uniform pattern of reactogenicity has gone undetected, is uncertain.

    Post-marketing surveillance for adverse reactions occurring in the United States will be established by the manufacturer.

    VACCINE USAGE U.S. Expatriates

    JE vaccine is recommended for persons who plan to reside in areas where JE is endemic or epidemic (residence during a transmission season) (40-44). Risk for acquiring JE is highly variable within the endemic regions (Table 1, Figure 1). The incidence of JE in the location of intended residence, the conditions of housing, nature of activities, and the possibility of unexpected travel to high-risk areas are factors that should be considered in the decision to seek vaccination. Travelers JE vaccine is NOT recommended for all travelers to Asia. In general, vaccine should be offered to persons spending a month or longer in endemic areas during the transmission season, especially if travel will include rural areas. Under specific circumstances, vaccine should be considered for persons spending less than 30 days in endemic areas, e.g., travelers to areas experiencing epidemic transmission and persons whose activities, such as extensive outdoor activities in rural areas, place them at high risk for exposure. In all instances, travelers should be advised to take personal precautions; e.g., to reduce exposure to mosquito bites.

    The decision to use JE vaccine should balance the risks for exposure to the virus (Table 1, Figure 1) and for developing illness, the availability and acceptability of repellents and other alternative protective measures (44), and the side effects of vaccination. Risk assessments should be interpreted cautiously (Table 1, Figure 1) since risk can vary within areas and from year to year and available data are incomplete. Estimates suggest that risk of JE in highly endemic areas during the transmission season can reach 1 per 5,000 per month of exposure; risk for most short-term travelers may be less than or equal to 1 per million. Although JE vaccine is reactogenic, rates of serious allergic reactions (generalized urticaria or angioedema) are low (1 to 104 per 10,000). Advanced age may be a risk factor for developing symptomatic illness after infection. JE acquired during pregnancy carries the potential for intrauterine infection and fetal death. These special factors should be considered when advising elderly persons and pregnant women who plan visits to areas where JE is endemic. Primary Immunization Schedule

    The recommended primary immunization series is three doses of 1.0 mL each, administered subcutaneously on days 0, 7, and 30. An abbreviated schedule of days 0, 7, and 14 can be used when the longer schedule is impractical or inconvenient because of time constraints. Two doses administered a week apart will confer short-term immunity among 80% of vaccinees (Table 3). However, this schedule should be used only under unusual circumstances and is not routinely recommended. The last dose should be administered at least 10 days before the commencement of travel to ensure an adequate immune response and access to medical care in the event of delayed adverse reactions.

    The immunization schedule for children 1-3 years of age is identical except that the manufacturer recommends 0.5 mL administered subcutaneously. No data are available on vaccine safety and efficacy in infants less than 1 year of age. Booster Doses

    Protective levels of neutralizing antibody persist for at least 2 years in vaccinees who have completed a three-dose primary series. The full duration of protection is unknown, therefore, definitive recommendations cannot be given on the timing of booster doses. Booster doses of 1.0 mL (0.5 mL for children less than 3 years of age) may be administered after 2 years.

    PRECAUTIONS AND CONTRAINDICATIONS Adverse Reactions and Hypersensitivity

    Adverse reactions to JE vaccine manifesting as generalized urticaria and angioedema have occurred within minutes to as long as 2 weeks after vaccination. Epinephrine and other medications and equipment to treat anaphylaxis should be available. Vaccinees should be observed for 30 minutes after vaccination and warned about the possibility of delayed urticaria and angioedema of the head and airway. Vaccinees should be advised to remain in areas with ready access to medical care in the 10 days after receiving a dose of JE vaccine.

    Persons with a history of certain allergic disorders (see ADVERSE REACTIONS) appear to have a greater risk for developing adverse reactions to JE vaccine. This history should be considered when weighing the risks and benefits of the vaccine for an individual patient. When patients with such a history are offered JE vaccine, they should be alerted to their increased risk for reaction and monitored appropriately. There are no data supporting the efficacy of prophylactic antihistamines or steroids in preventing JE vaccine-related allergic reactions.

    JE vaccine is produced in mouse brains and should not be administered to persons with a proven or suspected hypersensitivity to proteins of rodent or neural origin (other vaccines produced in rodent neural tissue include experimental hantaviral vaccines produced in Korea and the PRC and the previously used French neurotropic strain yellow fever vaccine {discontinued in 1982}). Hypersensitivity to thimerosal is a contraindication to vaccination.

    The vaccine should not be administered to persons who have had a previous adverse reaction after receiving JE vaccine. Patients who develop allergic or unusual adverse reactions after vaccination should be reported through the Vaccine Adverse Event Reporting System (1-800-822-7967). Age

    No data are available on the safety and efficacy of JE vaccine among infants less than 1 year of age. Whenever possible vaccination of infants should be deferred until they are greater than or equal to 1 year of age. Pregnancy

    No specific information is available on the safety of JE vaccine in pregnancy. Vaccination poses an unknown but theoretical risk to the developing fetus, and the vaccine should not be routinely administered during pregnancy. Pregnant women who must travel to an area where risk of JE is high should be vaccinated when the theoretical risks of immunization are outweighed by the risk of infection to the mother and developing fetus. Altered Immune States

    The only data on the use of inactivated JE vaccine in patients with altered immune states come from a small study among children. These data did not suggest a changed pattern of adverse reactions or immune response after vaccination (45). Simultaneous Administration of Other Vaccines or Drugs

    Limited data suggest that the immunogenicity and safety of JE vaccination is not compromised by simultaneous administration with DTP vaccine (Nisalak A, unpublished data). No data exist on the effect of concurrent administration of other vaccines, drugs (e.g., chloroquine, mefloquine), or biologicals on the safety and immunogenicity of JE vaccine.


    Twenty-two cases of laboratory-acquired JE have been reported (46). Although work with JE virus is restricted to facilities with BL-3 capabilities, JE virus may be transmitted in a laboratory setting through needlesticks and other accidental exposures. Vaccine-derived immunity presumably protects against exposure through these percutaneous routes. Exposure to aerosolized JE virus, and particularly to high concentrations of virus, that may occur during viral purification, potentially could lead to infection through mucous membranes and possibly directly into the central nervous system through the olfactory epithelium. Whether vaccine-derived immunity protects against such exposures is unknown, but vaccination is recommended for all laboratory workers with a potential for exposure to infectious JE virus.

  5. #5
    Thanks Dr. Young. In Sri Lanka the 2nd dose is given two weeks after the first dose. The 3rd one after 1 year and the 4th after 2 years. The government was giving these injections in their clinics but have stopped from this year. A private hospital I spoke to told me to ask Sachi's paediatrician whether this should be given or not because of the side effects. Although Japanese Encephalitis cases are reported in Sri Lanka it is mainly in the Northwestern and Central provinces. We live in the Western Province and no cases have been reported here.

  6. #6
    Quote Originally Posted by juliefittler
    After my first child had her vaccinations she started having fits, when I asked the docotr about it he said there as no way it was from the vaccinations, after reading up on it I went to a pediatrician and he explained that it mayhave been the case, there are so many undisclosed side effects from vacines it is unbelivable, but I guess you have to weigh up all the pros and cons and go from there. I do think that the mediacl profession should be more honest about the situation though, or atleats warn there are some side effects that are not mentioned in the pamplets they give you.


    PS Im new here but this post intrested me, so I had to put my 2 cents in
    Julie, I agree that vaccination brochures don't give detailed data of complications and can be misleading. On the other hand, even if the data were available, it is very difficult for parents to evaluate risk. Correlation does not mean cause-and-effect. For example, there are many causs of seizures in children and, since every chlld gets vaccines, vaccines are often blamed for seizures. Likewise, since almost every child over ten years old has gotten vaccine that included mercury as a preservative, this has been blamed as a cause of autism. Risk is hard to evaluate.

    The most difficult question is the one that Sisira is asking. According to the published vaccine trial results, it is only about 80% effective. In other words, when a population of 100,000 children were vacinated in an endemic area, the incidence went from 18 to 4. Four kids still got the disease. 100,000 vaccinations saved only 14 kids. This means that the risk of getting the disease is quite low to begin with, only 18 out of 100,000. Adverse events occurred in perhaps as many as 10% of the vaccinated population. Serious adverse events, however, was much lower. Is it worth the the risk of side-effects?

    If your child gets encephalitis because you turned down the vaccine, you will feel bad. On the other hand, if the child gets a serious side-effect, the manufacturer is almost invariably sued. By the way, this is why vaccines are so expensive. Few manufacturers are willing to make vaccines and, when they do make vaccine, it is often only if Congress paid for the expense and indemnifies the company against lawsuits. It is a difficult decision and so I can only speak for myself as a parent and not as a doctor.

    I decided that my kids would get all the available vaccines, as long as the incidence of serious side-effects is less than the incidence of the disease. This is plain common sense. I do this not only for their protection but also for public health reasons. When a large segment of the population is immune, the disease cannot spread. This further reduces the risk of the disease affecting my kids. The worse the disease, the more strongly I feel that my kids should get the vaccine. Of course, if my kids has ever had any adverse reaction to any vaccine, I would reconsider the situaton very carefully. if they have had one adverse response to a vaccine, I would probably allow only the most essential vaccines after that. However, if my kid has never had any adverse reaction, I encourage their doctor to give them all approved and recommended vaccines.

    In the specific case of the Japanese encephalitis, my review of the literature suggests that the vaccine is reasonably effective, that the incidence of adverse events is lower than the incidence of the disease, and that the Sri Lanka was once an endemic area for the disease. Please note that the reason why certain areas don't have the disease is because many kids have been inoculated. Since this is a mosquito-carried disease, I suspect that it is not because the mosquitos in part of Sri Lanka cannot carry the disease. Your area may not have a high incidence of the disease because of the vaccination. However, as pointed out above, if your child has had any adverse reaction, such as seizures, urticaria (rash), or high fever, associated with any vaccine in the past, that would be good reason not to have this vaccine.

    Last edited by Wise Young; 08-22-2007 at 10:19 AM. Reason: typographical and grammatical errors

  7. #7
    Thank you Dr. Young. And also thank you Julie for sharing your experiences with vaccines.

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