Why are there so many childhood vaccines now?
If you compare a modern immunisation schedule with the one you were given as a child, there are noticeably more entries. This is not a sign that something has gone wrong. It is the result of decades of research producing safe vaccines against diseases that used to be simply accepted as part of childhood - or as part of childhood death.
What has been added, and why
Hib vaccine arrived in the 1990s and almost eliminated what had been the commonest cause of bacterial meningitis in under-fives. Pneumococcal vaccine followed, cutting a major cause of pneumonia, the biggest infectious killer of small children worldwide. Meningococcal B vaccine, licensed in the 2010s, closed the last big gap in protection against the infection that can go from a slight fever to intensive care in a matter of hours. Rotavirus drops removed the leading cause of babies being admitted to hospital with dehydration. Each addition targeted a specific, documented, serious threat.
Why the number of injections has not grown as fast as the number of diseases
Combination vaccines do a lot of quiet work. A single '6-in-1' injection covers diphtheria, tetanus, whooping cough, polio, Hib and hepatitis B. Where a baby once needed separate shots for each, they now need one. Schedule designers work hard to bundle vaccines into the fewest possible appointments, which is also why several are given at the same visit.
Does this overload a baby's immune system?
No. The number of immune 'targets' (antigens) in the whole modern schedule is actually far lower than in the schedules of the 1980s, because older vaccines were less refined. A baby's immune system responds to an enormous number of new challenges every single day from normal life. The vaccine schedule is a small, deliberate, well-tested addition to that.
The bottom line
More vaccines on the schedule means more diseases your child will never have to face. The schedule looks longer because medicine got better, not because the burden on your child got heavier.