Previously vaccination against pertussis was not recommended for those over 6 years of age, they add, because of concerns of increased reactogenicity of the whole-cell vaccines.

The vaccination response of new absorbent pertussis mixed vaccine preparation was lower and its serological effect was better as well.

"However, 'they conclude," if such an increased risk exists, the absolute risk is extremely small and it is much lower after vaccination than after pertussis or measles.