Vaccine, Vol. 13, No. 6, pp. 593596, 1995 Coovrioht 0 1995 Elsevier Science Ltd zyxwvutsrqpon 0264-410X(94)00049-2 Printed in Great Britain. All rights reserved 026441ow95 $10.00+0.00 zyxwvutsrqpon Efficacy study of a new albumin-free Human Diploid Cell Rabies Vaccine (Lyssavac-IHDC, Berna) in 100 severely rabies-expensed Thai patients Henry Wilde, Reinha.rd Glueck, Pakamatz Khawplod, Stanley J. Cryz, Terapong Tantawichien, Penmas Thipkong, Pranee Chomchey, Sompop Prakongsri, Maneerat Benjavongkulchai, Aree Sumboonanondha, Ponsri Samranwetaya, Kantorn Supakorn and Visith Sitprija zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGF 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 J-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’ 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 I year and remained well. No significant side-effects from this vaccine were noted. Keywords: Human Diploid Cell Rabies Vaccine; rabies vaccine; Thailand; rabies vaccine reactions; serum sickness; rabies vaccine efficacy Rabies vaccines produced in human diploid cells (HDCV) have been available for two decades and have become known for their immunogenicity, efficacy and safety. Virtually the only significant adverse side-effects to previous HDCV have been serum sickness-like reactions after repeated booster doses due to antibodies to betapropriolactone-altered human albumin which is added as a stabilizer. A new HDCV (Lyssavac-HDC) from the Swiss Serum and Vaccine Institute utilizes the Pittman-Moore 90 RA 4EE2 strain of rabies virus and a different technique for inactivation and stabilization. The virus in Lyssavac-HDC is harvested and purified by ultracentrifugation on a sucrose gradient. It is inactivated with betapropriolactone and then mixed with a stabilizer containing gelatin, L-cysteine, potassium phosphate and lactose. The end product is lyophilized and packaged together with a sterile water diluent of 0.5 ml. Each reconstituted ampule contains at least 2.5 international units of rabies antigen and conforms to all World Health Organization (WHO) requirements for accept,snce as a rabies vaccine for human use’. This report describes our l-year experience with a prospective efficacy study of 100 severely rabies-exposed Queen Saovabha Memorial Institute (WHO Collaborating Center For Research in Rabies), The Thai Red Cross Society and the Department of Medicine, Chulalongkorn University, Bangkok, Thailand. (Received 13 May 1994; revised 9 September 1994; accepted 9 September 1994) Thai subjects seen at the Queen Saovabha Memorial Institute (QSMI) which serves as Bangkok’s primary animal bite management center. MATERIALS AND METHODS Patient population One hundred patients with WHO Category III rabies exposures’ were included in this study. All had incurred transdermal bleeding wounds at various body sites within 3 days of presenting for treatment. The wounds had been inflicted by a dog or cat that was available for necropsy and was found positive by fluorescent microscopy for rabies antigen at QSMI or at a regional laboratory of the Thai Ministry of Public Health. Exclusion criteria were a previous history of pre- or post-exposure rabies vaccination and unstable residence or employment history. Most of the subjects came from the lower socio-economic group. Informed consent participation in this study was obtained from all subjects. This study was approved by the Ethics and Human Experimentation Committee of the Science Division, Thai Red Cross Society. Post exposure treatment regimen All patients were interviewed by nurse practitioners experienced in rabies post-exposure management and problem cases (deep wounds, wound infection or complications) were also seen by one of the physician Vaccine 1995 Volume 13 Number 6 593