The number of cases of meningitis and blood poisoning is decreasing, and this is clearly due to the inclusion, since 2006, of pneumococcal disease into the child immunisation programme.
Rebecca Ashley Gladstone is a postdoctoral fellow at the department of Biostatistics at IMB. Photo: Anne Wennberg, UiO
- Before it was included in the child immunisation programme, there were over 1,000 cases a year, compared to about 600 per year in 2022 and 2023. The decrease in cases is particularly apparent amongst children under the age of ten. In this age group, there were for example 136 cases of invasive pneumococcal disease in 2005, compared to 40 cases in 2022 and 27 in 2023, explains Vegard Eldholm, a research scientist at the Norwegian Institute of Public Health (FHI).
These statistics are revealed in a study carried out as a collaboration between FHI, the Institute of Basic Medical Sciences (IMB) and others.
The vaccine protects several risk groups
- The most important thing that our genome analyses show is that the inclusion in the child immunisation programme has protected not only children, but also the elderly. Since fewer children fall ill, this leads to fewer infections being passed on to their grandparents for example, who are also a group at risk, says Rebecca Ashley Gladstone, postdoctoral fellow at IMB.
The extensive data base of samples, dating all the way back to the 1980s, which the researchers have been studying since 2018, also provides a great deal of knowledge about the development of pneumococcal bacteria and a basis for further developing the vaccine.
The bacterium's capsule is crucial
On the outside of the pneumococci there is a capsule of polysaccharides, which in many ways resembles the spike protein we heard so much about during the covid pandemic. This spike was also one of the reasons why the virus was constantly mutating and creating new variants.
- It is precisely this spike that the pneumococcal vaccine recognises - in fact, the current vaccine recognises 13 of nearly 100 existing capsule types or serotypes, as groups of pneumococci with a similar capsule are called. These 13 serotypes were originally chosen because they were the ones that were most often the cause of serious illness, explains Eldholm.
All in all, immunising with PCV (Pneumococcal Conjugate Vaccine) has quite clearly reduced the incidence of invasive pneumococcal disease, both among the young and the old. But the study also shows that pneumococci slowly but surely "escape" from the vaccine by developing new serotypes, or by an increase in rare serotypes leading to a higher incidence of disease.
New vaccines in the pipeline
- The study demonstrates that constant monitoring of the pneumococcal population is essential. PCV-13 is not the only pneumococcal vaccine available, and by studying how pneumococci mutate over a period of time, we will have much better knowledge on which to base our choice of the best possible vaccine for the next phase of the immunisation programme, says Gladstone.
She adds that the new vaccines, with the capacity to recognise more capsule types, are in the pipeline and the most recent one, recognising 20 capsule types, was approved by the European Commission this year.
Pneumococci also cause pneumonia, but it is meningitis and blood poisoning that must be reported to the health authorities.
An in-depth study of pneumococci
The first author Eldholm, together with Gladstone and others at the Department of Biostatistics at IMB, has published an article in Genome Medicine. NMBU has also participated in the in-depth research on old pneumococci, which were sent in from Norwegian hospitals and stored in the basement at FHI for several decades.
