There were 1,781 confirmed cases of pertussis in England and Wales in the first five months of 2012 and 702 cases in May alone. There were 221 in the first five months of 2011, when cases began to rise, and 136 in the same period in 2010.
The rise in cases in 2011 predominantly affected adolescents and adults. But the increase in 2012 has extended into infants under three months, who are at highest risk of severe complications. Five pertussis-related deaths in infants were reported ii the first five months of 2012.
Pertussis cases rise every three or four years. However, the current rise is the highest since pertussis vaccination began to be given as part of an accelerated vaccine schedule in 1990.
The Health Protection Agency (HPA), which released the data, said that waning immunity is likely to be contributing to the rise.
HPA researchers have previously suggested that jabs should be given to adults and adolescents to boost immunity and protect babies too young to be vaccinated.
In January, HPA researchers said universal adolescent vaccination could be considered. But they added: ‘Better understanding of the disease at older ages is needed to assess the potential effect of additional vaccine doses and the role of adolescents in disease transmission to infants.'
In September 2010, HPA researchers also raised the possibility of extending pertussis vaccination to adolescents, as well as pregnant women and other adults.