Pranee Chomchey

What is an acceptable delay in rabies immune globulin administration when vaccine alone had been given previously

Rabies immune globulins (RIG) are not always available. Rabies-exposed patients often present to medical centers, particularly in canine rabies infested regions, after a vaccine series has been started without immune globulin administration. It is known that rabies immune globulin can result in suppression of the neutralizing antibody response which usually yields detectable antibodies by day 7. We have shown that it can be administered with a delay of up to 5 days after the start of vaccine treatment without significant antibody suppression within the first month. This study utilized the WHO approved multisite Thai Red Cross intradermal postexposure regimen. Effective use of rabies immune globulin in severe and multiple wounds, particularly in small children, may require dilution of the RIG in normal saline to provide a volume adequate for infiltration of all wounds.

Adverse effects of equine rabies immune globulin

Following a recently published prospective study of 485 recipients of equine rabies immune globulin (ERIG) manufactured by Pasteur Vaccins (Paris), this paper reports a study of 323 postexposure rabies patients receiving ERIG manufactured by the Swiss Vaccine and Serum Institute (Berna). It is concluded that there may be significant differences in adverse reaction rates, reflecting differing manufacturing or purification processes and protein content. Further studies of different ERIG products and of different lots of the same product are needed while ERIG remains an essential component of postexposure rabies treatment in developing countries.

Prospective Immunogenicity Study of Multiple Intradermal Injections of Rabies Vaccine in an Effort to Obtain an Early Immune Response without the Use of Immunoglobulin

The present study sought to determine whether increasing and accelerating rabies vaccine administration would result in earlier protective levels of neutralizing antibody. Results indicated that the 8-site and double-dose Thai Red Cross intradermal regimens produced higher antibody titers by day 14 but not significantly higher titers by days 5 and 7. Administration of rabies immunoglobulin into and around bite wounds on the first day of rabies prophylaxis should remain the optimal postexposure treatment.

Antibody Response After a Four-Site Intradermal Booster Vaccination with Cell-Culture Rabies Vaccine

The current World Health Organization recommendation for booster vaccination of previously immunized individuals with potential exposure to rabies is two doses of vaccine intramuscularly or intradermally on days 0 and 3. We report responses to two types of postexposure treatment of healthy individuals who had received preexposure rabies vaccination 1 year previously. Group A individuals received four intradermal doses (one-fifth of the diluent volume of vaccine per dose) on day 0, and group B individuals received two intramuscular doses on days 0 and 3. Immunogenicity of the two booster regimens was assessed by titrating the amount of neutralizing antibody (Nab). We found that the booster doses of vaccine produced remarkable responses in all subjects. Nab titers of > or = 0.5 IU/mL (acceptable antibody level for protection against rabies) were detected in all subjects on day 14, and they were shown to be consistently high 1 year after the booster vaccination. We also found that the Nab titers for group A were significantly higher (two- to eightfold) than those for group B on days 5, 14, 150, and 360 after the initial booster vaccination (P < .05). Our study shows that the four-site intradermal booster regimen with use of one-fifth of the diluent volume of cell-culture rabies vaccine on day 0 is associated with a significantly higher antibody response than is the conventional booster regimen for subsequent postexposure rabies treatment of individuals who have received preexposure rabies vaccination with cell-culture rabies vaccine 1 year previously.

Immune response to tissue culture rabies vaccine in subjects who had previous postexposure treatment with Semple or suckling mouse brain vaccine.

Nerve tissue derived Semple and suckling mouse brain rabies vaccines are still widely used. Patients who experience a new rabies exposure and who were given such vaccines decades earlier are not uncommon in rabies endemic countries. The World Health Organization recommends that persons who have had a previous course of a potent tissue or avian culture rabies vaccine and are reexposed, be given booster infections on days 0 and 3 without rabies immune globulin. Persons who have had previous pre- or postexposure vaccination with a vaccine of unproven potency, should receive a full course of tissue or avian cell vaccine and immune globulin in the event of a new exposure. This study evaluated the immune response in 98 Thai patients who gave a history of rabies postexposure treatment with Semple or suckling mouse brain vaccines 10-50 years previously. The majority (81) had an anamnestic response and developed neutralizing antibodies that were above the recommended minimal acceptable level (0.5 IU ml-1) on day 7. This suggests that they still had immunological memory. A minority of 18% had antibody titers below this level on day 7. However, they all developed titers above 0.5 IU ml-1 on days 14 and 30. Failure to have an accelerated response to revaccination by day 7 did not appear to be related to age or time elapsed since previous nerve tissue derived vaccine administration. It was not possible to predict which subject will or will not have an acceptable level of antibody before day 14. Rabies exposed patients who give a prior history of vaccination with an unknown or nerve tissue derived vaccine should therefore be treated as if they had never been vaccinated.

An immunogenicity and efficacy study of purified chick embryo cell culture rabies vaccine manufactured in Japan

Purified chick embryo cell rabies vaccine manufactured by the Chemo-Sero-Therapeutic Institute(Kaketsuken) at Kumamoto, Japan (Kaketsuken) was submitted to an immunogenicity and efficacy study. 52 severely rabies exposed patients were treated with the conventional five doses intramuscular WHO approved (Essen) postexposure schedule. This included the administration of 40 IU kg-1 of equine rabies immune globulin on Day 0. A control group of equally severely exposed subjects were treated with human diploid cell rabies vaccine manufactured by the Swiss Serum and Vaccine Institute as well as human rabies immune globulin. There were no deaths in either group in the more than 2 years follow-up period. Subjects treated with the chick embryo vaccine showed greater suppression of the neutralizing antibody response by the equine rabies immune globulin than those given the human diploid cell vaccine and human rabies immune globulin. A group of 20 less severely rabies exposed patients who received only the chick embryo vaccine without immune globulin all had antibody titers greater than the WHO minimal acceptable level on Day 14, 30, 90 and 180. Fourteen subjects among the severely exposed vaccine and immune globulin study group were given vaccine boosters on Day 180 because of low antibody titers. It is concluded that chick embryo rabies vaccine manufactured by Kaketsuken is an immunogenic and effective rabies vaccine, but that the potency of future batches must be increased to provide a greater safety margin.

Efficacy study of a new albumin-free Human Diploid Cell Rabies Vaccine (Lyssavac-HDC, Berna) in 100 severely rabies-exposed Thai patients

A newly developed human diploid cell rabies vaccine (Lyssavac-HDC), produced without added serum albumin and with an effort to remove the virus-inactivating beta-propriolactone prior to addition of the gelatin, L-cysteine and potassium phosphate stabilizer, was tested for safety immunogenicity, adverse reactions and efficacy in 100 severely rabies-exposed Thais. All patients also received human rabies immune globulin and vaccine was administered using the conventional 5-dose intramuscular schedule of one dose on days 0, 3, 7, 14 and 28. One hundred percent of a subgroup of 40 subjects, where blood had been collected, had neutralizing antibodies greater than 0.5 IU ml-1 on days 28 and 90 and all had detectable titers on days 7, 14, 28, 90, 180 and 360. All patients could be followed for at least 1 year and remained well. No significant side-effects from this vaccine were noted.