Comparison of acellular and whole-cell pertussis-component diphtheria-tetanus-pertussis vaccines in infants

Pertussis, also known as whooping cough, is an infection caused by the bacteria, Bordetella pertussis. It is characterized by initial symptoms of fever, sneezing, inflammation of the mucous membranes of the nose, dry cough, irritability, loss of appetite. Attacks of whooping, which consists of short coughs followed by long drawn inhalation of air and a whooping sound, then occur over two weeks. The disease resolves within several weeks to months. Vaccines to prevent pertussis have been developed, but may cause side effects. Acellular vaccines, which contain parts of the bacteria rather than the whole cell, have been shown to have minimal adverse effects. An acellular pertussis vaccine was developed to protect against pertussis; diphtheria, an infection with the bacteria Corynebacterium diphtheriae; and tetanus, an infection with the bacteria Clostridium tetani. This combined vaccine is referred to as the acellular pertussis-component diphtheria-pertussis-tetanus (APDT) vaccine. It is produced by the Japanese drug company Takeda Chemical Industries and the American drug company Lederle Laboratories. The effectiveness of the Lederle/Takeda APDT vaccine was compared with a diphtheria-pertussis-tetanus (DPT) vaccine containing whole cells of pertussis. The study involved 252 children who were vaccinated at two, four, and six months of age with the whole-cell vaccine; 245 received the acellular vaccine using the same schedule. All children were immunized with the acellular vaccine at 18 months of age. The incidence of adverse effects was lower among children initially immunized with the acellular vaccine compared with children given the whole cell vaccine. The severity of unfavorable vaccine-related side effects was reduced after the 18-month immunization in all children. The whole-cell and acellular types of vaccines differed in their abilities to produce certain immune responses. These findings show that the APDT causes fewer adverse side effects than the conventional whole-cell DPT vaccine. The relative protective effects of the two vaccines require further study. (Consumer Summary produced by Reliance Medical Information, Inc.)