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Pertussis (whooping cough)
Pertussis is caused by infection with the bacterium Bordetella pertussis. It is spread by droplets and direct contact and is highly contagious.
Each year, about 286 000 people, almost all young infants, are killed by the disease worldwide, and at least 45 million suffer from the illness with prolonged and exhausting bouts of coughing that may continue for up to 3 months. Some children also suffer seizures and neurological damage.
In recent years there have been reported increases in the incidence of pertussis, including in several industrialized countries. Immunity to infection is not permanent, even after infection with B. pertussis. This partly explains the number of cases observed in adolescents and adults in some countries.
Vaccines based on whole killed B. pertussis bacteria (known as "whole-cell vaccines") have been used effectively and safely for several decades to prevent infection.
Frequent, but usually mild, adverse reactions associated with these vaccines, such as fever and localized side effects (redness, swelling and pain at the site of injection) and a fear of extremely rare but serious neurological events, reduced public acceptance of these vaccines in the 1970s in some countries, and led to the development of a new generation of vaccines that contain components of the bacterium instead of all of it. These products, known as "acellular" vaccines, provoke fewer of the frequent mild-to-moderate reactions seen with the whole-cell vaccines, while severe adverse effects are equally rare in both types of vaccine. The best acellular vaccines are as effective as the best whole-cell vaccines. Acellular vaccines are considerably more costly, however, and therefore whole-cell vaccines continue to be the most widely used. Both whole-cell and acellular vaccines can be given in combination with tetanus and diphtheria vaccines.
For more information see:
At a glance
Vaccine-preventable disease statistics
Glossaire des infections a prévention vaccinale
'Traditional' or 'basic' vaccines
Vaccines that are expected to be available shortly
Vaccines for which more research is needed