A study found that youngsters could be at risk of contracting the disease as they get older even if they received the vaccine as a child.

In 1999/2000, the Government ran a mass meningitis immunisation campaign to vaccinate children aged one to 18.

In the latest research, experts looked at the impact of introducing that jab on immunity levels among a group of almost 1,000 children. They discovered that youngsters who were aged six to eight when they were vaccinated as part of the national campaign were not sufficiently protected when they reached the ages of 11 to 13.

Dr Matthew Snape, from the Oxford Vaccine Group at the University of Oxford, who led the study, said the findings were also likely to apply to children who were younger than six to eight when they received the jab in 1999-2000.

Furthermore, babies born between 1999 and September 2005 could also be at risk, he said. Since 2005, a booster jab at 12 months of age has been introduced.

He said: "Our findings are mostly relevant to children who received a single dose in the 1999-2000 campaign.

"But it's likely that others younger than that will also have low or possibly even lower levels of antibodies.

"Then there are those born before September 2005 who just received the two, three and four-month jab but no booster dose."

The jab protects against meningitis C strain of the disease, although experts are currently working on a jab for the B strain, which is much more common.