Pertussis is an infectious disease, occurring mainly in children, caused by infection with the Gram-negative bacillus Bordetella pertussis. Despite the use of universal immunization, whereby every child in our country should be vaccinated against pertussis at least four times, there is still an incidence of this serious disease. In recent years, there has even been an alarming increase in cases of pertussis, including numerous cases in older children.

Epidemiology

Among the most important causes of pertussis cases are:

1) The presence in the paediatric population of non-immunized individuals - exempt from pertussis vaccination

Epidemiologists estimate that the risk of re-emergence arises when the percentage of children vaccinated against the disease falls below 90% of the population. In terms of pertussis vaccination in Poland, the situation is dangerously approaching this limit, and in some regions has already exceeded it.

2) Extinctionof post-vaccination immunity in older children

The extinction of post-vaccination immunity is a natural phenomenon. For children who have undergone a full course of vaccination, the eventual illness should be mild, but such patients may be a source of infection for other, non-immunized children.

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3) Failure of theDTP vaccine to be fully effective, even if the child has been vaccinated on time according to the current vaccination schedule

A peculiarity of pertussis vaccination is the relatively low percentage of full immunity, estimated at around 70%. The remaining 30% may contract pertussis despite vaccination, although obviously the illness will be much milder than in children not vaccinated at all.

4) Antigenic variability of the pertussis bacillus resulting in the possibility of contracting the disease even in people who are initially immunised

According to many scientists, it is necessary to develop a new pertussis vaccine formulation because the antigenic composition of the bacteria is changing and old vaccines may lose their effectiveness.