Vaccine-impervious meningitis C "superbugs" may pose a new threat to children, new research has suggested.
Scientists based in London's Imperial College have identified three strains with heightened resistance to vaccine-triggered immune responses.
At present there are no reports of emerging vaccine-resistant meningitis C in the community. However, experts fear if the strains get a foothold they could undermine the vaccine, introduced into the UK in 1999.
Each year more than 2,000 people, mostly children, are affected by all forms of meningitis in Britain. The disease claims about 300 lives per year and leaves hundreds of other victims with permanent disabilities.
No vaccine is currently available that can tackle the most common B strain of meningitis bacteria. But the meningitis C vaccine has reduced deaths in children by 95% and prevented more than 500 deaths.
Last year for the first time on record there were no deaths among people under the age of 19 caused by meningitis C.
A simple alteration in its DNA is thought to give the bug the potential to avoid attack by immune system antibodies.
The study, published in The Journal of Experimental Medicine, was funded by the charity Meningitis UK.