The triple antigen has been one of the standard vaccinations for children since the 1960s. It contains vaccines against tetanus, whooping cough (pertussis) and diphtheria.
It has now been superseded by vaccinations that contain four, five or even six vaccinations against even more diseases (e.g. chickenpox, hepatitis B, Haemophillus).
All children should receive the full course of vaccines to protect them against these serious diseases unless there are very good medical grounds not to use them.
The risk of vaccination is infinitesimal, and when compared to the potential side effects of any one of these diseases, it is a far preferable course of action.