|Pertussis and pertussis vaccination, particularly the almost simultaneous conduct of different clinical trials in various parts of Europe, has generated much debate in the past ten years. Nonetheless many important public health aspects still need to be clarified. The three papers reported in this issue of Eurosurveillance are good examples of the situations faced in different European countries and provide the following general lessons: Introduction of vaccination decreases incidence (as in Sweden); monitoring the incidence of pertussis may be difficult if elements of the surveillance system change (in Switzerland polymerase chain reaction (PCR) was added to improve diagnostic specificity and in the Netherlands serological criteria were added); outbreaks may occur even with a constant high vaccination rate (as in the Netherlands).Extensive vaccination is expected to bring about a fall in the incidence irrespective of the specific vaccine used, as all of the available products have been found to have an efficacy of at least 70%. Each vaccine will leave some individuals susceptible, however, the number inversely related to its efficacy. The effect will be seen only long term. Why the Dutch outbreak occurred and why the incidence in the Netherlands has remained high is still to be understood and the causative role of the genetic variants of Bordetella pertussis has to be quantified. The sensitivity of the current surveillance systems in many European countries will also need to be improved in the future, as the wider availability of acellular vaccines is likely to increase the proportion of children who are vaccinated (1) and vaccinated individuals are likely to present with milder illness. The expected decrease in pertussis incidence should therefore be investigated carefully using laboratory confirmation criteria. Preliminary (unpublished) results from the European Sero-Epidemiology Network (ESEN) project, which included a serosurvey in eight European countries, show continued circulation of B. pertussis in all countries despite high coverage although age specific incidence varied between countries. The survey has confirmed that many unrecognised infections occur.
In conclusion, basic research has provided efficacious vaccines but their provision is only the first step in the fight against pertussis. Controlling and eventually eliminating the disease is now the challenge for the public health.
|Stefania Salmaso, Istituto Superiore di Sanità, Rome, Italy1. Pertussis vaccination in Europe. Eurosurveillance 2000; 5 (in press)|