Effects of meningitis C jab may wear off

One in five 11–13 year olds appear to have low antibodies against meningitis C after being immunised as young children, suggests an Oxford University study published in the British Medical Journal.

In 1999–2000 the government ran a meningitis C immunisation campaign that vaccinated everyone between the ages of 1 and 18 years old and the number of cases dropped dramatically. Ever since, the vaccine has been part of the routine infant immunisation programme. Last year, for the first time, no one died of meningitis C disease.

However studies have shown that the vaccine’s effectiveness in infants drops over time as the level of protective antibodies in their bodies falls.

As teenagers used to be considered a group at high risk of contracting meningitis C, the researchers set out to determine whether those who had been immunised in 1999–2000 are still sufficiently protected against the disease as they reach adolescence.

Dr Matthew Snape and colleagues at the Oxford Vaccine Group took blood samples from 999 adolescents to see if they had antibody levels sufficiently high to provide protection against the disease.

The majority of all the 11–20 year olds had sufficient levels of antibodies to remain protected. However, approximately 90 per cent of the 14–20 age group had that level of protection compared to 80% of the 11–13 age group.

This means that over the coming years, a group of children will be entering adolescence in which over 20 per cent – ‘a significant minority’ – do not have sufficient levels of antibodies to protect them.

The researchers found that children who were aged 10 or over when vaccinated maintained protective levels of antibodies for longer, and suggest that one possible cause is maturation of the immune system at around the age of 10.

A booster dose of vaccine after the age of 10 may be needed to sustain protection against meningitis C amongst teenagers, say the researchers.

Source: Oxford University