Antibody response and characteristics of antibodies in women immunized with three contraceptive vaccines inducing antibodies against human chorionic gonadotropin**This study was conducted in five institutions with the clinical collaboration of the following physicians: Alok K. Banerjee M.D., National Institute of Health & Family Welfare, New Delhi; Kamala Dhall, M.D., Post Graduate Institute of Medical Education and Research, Chandigarh; Vera Hingorani, M.D., All India Institute of Medical Sciences, New Delhi; Usha R. Krishna, M.D., Seth G. S. Medical College & K.E.M. Hospital, Bombay; Shanti M. Shahani, M.D., T. N. Medical College & Nair Hospital, Bombay; and Badri N. Saxena, M.D., Indian Council of Medical Research, New Delhi.††Supported by grants from the S & T Mission Project of the Department of Biotechnology, Government of India, the International Development Research Centre of Canada and the Rockefeller Foundation, and benefited from cooperative interaction with the International Committee for Contraception Research of the Population Council, New York.