Design and Production of Single-Immunization Vaccines Using Polylactide Polyglycolide Microsphere Systems

Abstract

Over the past several years, many new adjuvant formulations have been developed to elicit both humoral and cell-mediated responses to antigens. Each of these new formulations must be given in repeated immunizations to yield antibody titers that result in protection. Typically, a minimum of three immunizations is required to invoke antibody titers or cellular responses that are sufficient to neutralize an infection. In addition, the patient may be required to return several years after the last immunization for a final booster immunization to again establish a neutralizing response. These repeated immunizations in developed countries may require repeated visits to the physician and increase the cost of health care. In developing countries and large urban areas, clinics are responsible for immunization of the children against many potentially fatal childhood diseases. Unfortunately, these clinics may have difficulty with repeated immunizations, since the patient population is transient or patients do not understand the necessity for additional shots. Thus, vaccine preparations requiring repeated immunizations are generally inefficient and may not always be successful in preventing disease because of poor patient compliance.