The number of confirmed cases in England and Wales this year is 7,728.
The HPA said 1,614 cases of whooping cough were reported in England and Wales in October.
In 2011, the total number of cases was 819.
In a move to combat the outbreak, Prof Sally Davies, the government's principal medical adviser, said women across the UK who are between 28 and 38 weeks pregnant will be offered the vaccination to protect their newborn babies.
Youngsters cannot receive the jab until they are two months old. Vaccinating their mothers before they are born will boost babies' immunity until they reach the age when they can have the injection themselves, she said.
While whooping cough can cause nasty symptoms in adults, it does not usually cause any long-lasting complications.
In the very young, whooping cough can be a serious illness and can lead to death in some cases.