Terapong Tantawichien

Failure of Pre- and Postexposure Rabies Vaccinations in a Child Infected with HIV

We report the case of a 6-y-old HIV-infected girl with severe immune deficiency who failed to respond to intramuscular pre-exposure rabies vaccination using human diploid cell rabies vaccine on days 0, 7 and 28. She also failed to respond to an intradermal postexposure rabies regimen using purified verocell rabies vaccine at 4 sites on days 0, 3 and 7 and at 2 sites on days 30 and 90 (double the usual regimen). Sequentially monitored rabies neutralizing antibody titers were below the WHO minimum acceptable level (> 0.15 IU/ml) in all specimens. Rabies prevention in HIV-infected persons with severe immune suppression requires further study.We report the case of a 6-y-old HIV-infected girl with severe immune deficiency who failed to respond to intramuscular pre-exposure rabies vaccination using human diploid cell rabies vaccine on days 0, 7 and 28. She also failed to respond to an intradermal postexposure rabies regimen using purified verocell rabies vaccine at 4 sites on days 0, 3 and 7 and at 2 sites on days 30 and 90 (double the usual regimen). Sequentially monitored rabies neutralizing antibody titers were below the WHO minimum acceptable level (> 0.15 IU/ml) in all specimens. Rabies prevention in HIV-infected persons with severe immune suppression requires further study.

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.

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.

Safety and immunogenicity of chromatographically purified Vero cell rabies vaccine for intradermal pre- and post-exposure rabies prophylaxis

Improved rabies pre- and post-exposure prophylaxis (PrEP and PEP) in developing countries uses an economic multi-site intradermal vaccination. Aim: To evaluate immunogenicity of chromatographically purified Vero cell vaccine (CPRV) for intradermal PrEP and PEP. Method: The subjects received conventional PrEP with CPRV or PVRV in PrEP study or received intradermal PEP with CPRV or PVRV and rabies immunoglobulin in PEP study. Result: All subjects who received PrEP with CPRV had protective neutralizing antibody (Nab) titers (≥0.5 IU/ml) 14 days after completing vaccination. In PEP study, Nab titers in the CPRV groups reached ≥ 0.5 IU/ml in all subjects by day 14 through day 90 after vaccination. The geometric mean titers of Nab in the CPRV groups had significantly higher titers than the PVRV group on day 14 through day 365 (p < 0.05). No serious adverse reactions were observed. Conclusions: CPRV is safe and immunogenic when given for intradermal PrEP and PEP.

Immunogenicity and safety of WHO-approved TRC-ID regimen with a chromatographically purified Vero cell rabies vaccine with or without rabies immunoglobulin in children

ABSTRACT Introduction: Children are at risk of rabies exposure in many Asian countries. The safety and immunogenicity profile of the WHO-approved two-site intradermal Thai Red Cross regimen (modified TRC-ID regimen; 2–2-2–0-2) with a new chromatographically purified Vero-cell rabies vaccine (CPRV) is lacking. Area covered: We studied the safety and immunogenicity of the TRC-ID regimen with a new CPRV in non-immunized Thai children with possible or proven rabies exposure. Thirty-nine seronegative patients (age range 2–14 years) with rabies exposure (WHO categories II or III) received two 0.1-mL intradermal doses of CPRV at both deltoid regions on days 0, 3, 7, and 28. Twenty-five patients (64.1%) received rabies immunoglobulin due to having rabies exposure, according to WHO category III. All serum samples were tested for rabies neutralizing antibody (Nab) by the rapid fluorescent focus inhibition test (RFFIT) before vaccination, and on days 14 and 90 after vaccination. All patients had an adequate immune response (Nab titers ≥ 0.5 IU/mL) on days 14 and 90. No patients died of rabies infection. No serious adverse reactions were observed. Expert commentary: CPRV is economic, safe, and immunogenic if given as the modified TRC-ID regimen in children.