Antibody response to suckling mouse brain rabies vaccines for post exposure treatment.

A new suckling mouse brain vaccine (SMBV) against rabies, produced by the Thai Red Cross Society, was compared with the well established Institut Pasteur SMBV in patients with very low risk rabies contact. The 4 regimens used were the standard daily injections with booster doses of Thai Red Cross vaccine (TRCV) and Institut Pasteur Vaccine (IPV), and a reduced dose scheme of 6 injections as used for tissue culture vaccines. The effect of 20 IU/kg of human rabies immune globulin (HRIG) was tested on each regimen, making 8 groups, a total of 122 patients. Blood samples taken on days 0, 7, 14, 28 and 91 were tested for neutralizing antibody. Only the standard IPV regimen produced antibody in every patient; all had levels greater than 0.5 IU at some stage. Two people (13%) given the standard TRCV produced no detectable antibody (less than or equal to 0.1 IU) throughout the study. The reduced dose regimens gave very low antibody levels. 7% of the IPV and 76% of the TRCV groups failed to produce antibody on any occasion. The antibody response was significantly suppressed by the administration of HRIG. Compared to the original South American SMBV, the vaccines tested induced low levels of short lived antibody. No reduction in the dosage of SMBV should be considered unless the potency of the product is adequate.

Economical multiple-site intradermal immunisation with human diploid-cell-strain vaccine is effective for post-exposure rabies prophylaxis.

An economical post-exposure regimen of Mérieux human diploid-cell-strain vaccine (HDCSV) was compared with Semple vaccine (SV), the most widely used vaccine in Asia. 155 patients bitten by animals proved to be rabid received either conventional courses of SV (34 severe and 43 mild cases) or HDCSV, 0.1 ml intradermally, at eight sites on day 0, at four sites on day 7, and at one site on days 28 and 91 (36 severe and 42 mild cases). All severely bitten patients were given equine anti-rabies serum (EARS), 80 IU/kg on day 0. There were no deaths from rabies in either group. Follow-up was 97.5% at 1 year and 93% at 2 years. 88% of patients given HDCSV alone had detectable neutralising antibody on day 7 in contrast to 2% given SV alone. Antibody persisted until 1 year in all sera tested from HDCSV patients in contrast to only 48% of SV sera. The high dose of EARS resulted in pronounced suppression of response to HDCSV. There were no serious systemic side-effects but local side-effects were significantly more common in the SV group. The multiple-site intradermal HDCSV regimen was at least as effective as SV. The amount of HDCSV used was 30% of the conventional dose.

Multi-site intradermal and multi-site subcutaneous rabies vaccination: improved economical regimens.

Neutralising antibody responses to six post-exposure regimens of human diploid cell strain rabies vaccine with or without human rabies immune globulin (HRIG) were studied in 98 patients. The total amount of vaccine used was 22-34% of that required by conventional regimens. Vaccine was given at multiple sites intradermally or subcutaneously with or without adjuvant. Antibody was detectable within 7 days of the first dose in all subjects only in the groups given 0.1 ml intradermally at 8 sites. From day 14 onwards all groups showed an excellent antibody response; there was little difference between the various regimens. Suppression of the response to 8-site intradermal vaccination by a large dose of HRIG could be prevented by giving the second dose of vaccine on day 7 rather than day 14.

An economical regimen of human diploid cell strain anti-rabies vaccine for post-exposure prophylaxis.

Vaccine regimens using 0.1 ml human diploid cell strain vaccine (HDCSV) given intradermally (id) in single and multiple sites, or with aluminum hydroxide adjuvant given subcutaneously (sc), were compared with the regimens of HDCSV and Semple vaccine currently suggested by WHO. Some groups were also given human rabies-immune globulin (HRIG). Neutralising antibody titres were monitored for 3 months. Antibody was detected earliest in subjects given 0.1 ml HDCSV id at each of eight sites. The highest antibody titres from day 14 onwards were found after intramuscular (im) administration of HDCSV, but the multiple-site id regimen, which requires only one quarter of the volume of vaccine required for the im regimen, gave similar results, provided that a booster was given on day 91. This finding suggests that a treatment schedule based on this regimen would be suitable for post-exposure prophylaxis. Adjuvanted vaccine gave similar results to the same amount of antigen given id. Semple vaccine produced the lowest titres. HRIG, given at the high dose of 40 IU per kg, suppressed the antibody response to some of the regimens.