The effectiveness of a vaccine is determined by many things, including how strong an immune response it produces (its ‘immunogenicity’), and how widely it covers disease-causing strains circulating in the country.
The MenB vaccine has been shown to be working well following its introduction to UK infants. Ten months after the programme was introduced, disease surveillance revealed that cases of disease had halved in vaccine eligible age groups. Based on this data, vaccine efficacy against all MenB strain after two doses of vaccine has been calculated to be 83%. However if it is taken into consideration that the vaccine is only predicted to protect against 88% of circulating strains in the UK1
then the efficacy is 94%, against the strains that it is predicted to cover2
Results from the vaccine trials were very encouraging, showing that the vaccine triggers a strong immune response in infants, toddlers and adolescents3-5
. Studies looking at how well circulating MenB strains match the vaccine have predicted that it will cover approximately 88% of MenB strains circulating in the UK1
, and 78% of MenB in Europe over all6
The actual proportion of cases prevented will depend on other things too, including how widely the vaccine is offered and taken up, whether it prevents the bacteria from being carried and passed on and how long protection lasts.
Uptake of the MenB vaccine in the UK is high. Nearly 89% of eligible UK infants had received two doses of the vaccine 10 months after the programme had been introduced. But only babies are routinely offered the vaccine so older age groups remain unprotected.
It may be possible to protect older age groups by immunising teenagers. Teenagers are more likely to carry meningococcal bacteria in the back of the nose and throat and transmit the bacteria to others. However, if the vaccine prevented teenagers from carrying the bacteria, transmission and spread of disease amongst the whole population could be slowed by immunising them. The UK government have commissioned a study to find out whether vaccinating teenagers will stop them from carrying the bacteria. MRF funded some preliminary research which will help inform the methodology for the large UK study here