The expected four-yearly outbreak of whooping cough failed to materialise for the first time in 1994, after medical researchers succeeded in dispelling fears that immunisation against the illness caused brain damage.

There had been a sharp fall in notifications of the disease from the 1950s on, when immunisation was introduced, but scare stories in the early 1970s led to a decline in immunisation uptake.

Outbreaks of whooping cough followed in 1978 and 1982, and it was not until 1985 that new evidence showed immunisation did not cause brain damage and public confidence returned.