Pertussis vaccine

Pertussis vaccine is a vaccine that protects against whooping cough (pertussis). There are two main types: whole-cell vaccines and acellular vaccines. The whole-cell vaccine is about 78% effective while the acellular vaccine is 71–85% effective. The effectiveness of the vaccines appears to decrease by between 2 and 10% per year after vaccination with a more rapid decrease with the acellular vaccines. The vaccine is only available in combination with tetanus and diphtheria vaccines. Pertussis vaccine is estimated to have saved over 500,000 lives in 2002. Vaccinating the mother during pregnancy may protect the baby. The World Health Organization and Centers for Disease Control and Prevention recommend all children be vaccinated for pertussis and that it be included in routine vaccinations. Three doses starting at six weeks of age are typically recommended in young children. Additional doses may be given to older children and adults. This recommendation includes people who have HIV/AIDS. The acellular vaccines are more commonly used in the developed world due to fewer adverse effects. Between 10 and 50% of people given the whole-cell vaccines develop redness at the injection site or fever. Febrile seizures and long periods of crying occur in less than 1% of people. With the acellular vaccines a brief period of non-serious swelling of the arm may occur. Side effects with both types of vaccines, but especially the whole-cell vaccine, are less common the younger the child. The whole-cell vaccines should not be used after seven years of age. Serious long term neurological problems are not associated with either type. The pertussis vaccine was developed in 1926. It is on the World Health Organization's List of Essential Medicines. Acellular pertussis vaccine (aP) with three or more antigens prevents around 85% of typical whooping cough cases in children. It has higher or similar efficacy to the previously used whole cell pertussis vaccine, however the efficacy of the acellular vaccine declines faster.