Are meningococci more abundant in the throats of teenagers with common wintertime viruses?

What is this project about?

Although meningococcal disease mostly occurs in young children the bacteria are most commonly found living in the throats of adolescents and young adults. They are transmitted between these young people, and to others, though social contact but only rarely cause disease. 

It is now known that the success of the vaccination programme against MenC was largely due to the vaccine’s ability to reduce carriage and transmission between adolescents and also from adolescents to others including younger children. For this reason, interest in understanding how meningococcal bacteria are carried and transmitted has increased. 

The research team have recently shown that adolescents are more likely to have higher numbers of meningococcal bacteria in their throats in January and February. This time of ‘high density carriage’ coincides with the peak of the influenza season. 

The aim of this project is to establish whether wintertime viral infections (such as influenza) could be associated with high carriage density of meningococcal bacteria. In other words, are people with wintertime viral infections more likely to carry high numbers of meningococcal bacteria and therefore be more infectious?

Why is this important?

With meningococcal disease, it is widely accepted that prevention is better than cure and prevention primarily means vaccines. It’s now clear for many vaccines that it is when the train of transmission is broken that really impressive disease prevention occurs and meningococcal vaccines are no exception. As a result there is an urgent need to understand better how throat carriage of meningococcus happens and find new ways of preventing it.

Potential outcomes

If viral infections like flu cause meningococcal carriage to be more common or cause people to carry higher numbers of meningococcal bacteria and so, probably, to be more infectious than others, then widespread use of flu vaccines may result in reductions in the circulation of meningococcus and so less disease. The way we use meningococcal vaccines might also be changed to focus efforts more efficiently on blocking transmission at critical times and places.

Decisions about whether or not to use vaccines depend increasingly on mathematical models. Essentially these are large sums that work out how much disease and how many deaths will be prevented and how much all of that is worth compared to the cost of buying and administering the vaccine. Often it is hard to get these sums right because it is not known exactly how well the vaccines will work. This is especially true about their ability to reduce disease by reducing circulation of the bacteria that cause disease in the population. The results of this study will help improve the information used in these kind of sums and so increase the confidence with which policy decisions about new vaccines can be made.