Other age groups than children need to be considered as carriers of Streptococcal pneumoniae serotypes

Abstract

We need to raise the issue that focus on children as the only carriage group for pneumococci is not optimal; we need to consider that other age groups might also be carriers of pneumococcal serotypes causing invasive pneumococcal diseases (IPD) in unvaccinated age groups. The pneumococcal conjugate vaccines (PCV) have successfully removed IPD from vaccinated children. Studies have shown an effect of PCV reducing the pneumococcal carriage of PCV serotypes in children. The status for several countries having used PCV for many years is that they do not see PCV serotypes neither carried nor as a cause of IPD in children.PCV vaccination of children has shown a herd protection effect in unvaccinated groups as a reduction in IPD cases caused by PCV serotypes. However, not all PCV serotypes have disappeared as the cause of IPD in the unvaccinated age groups. The author therefore believes that if we are to see PCV serotypes disappear as a cause of IPD in unvaccinated age groups, we need to perform further carriage studies to examine carriage in other age groups. Alternatively, all age groups should be vaccinated against pneumococci to eliminate IPD caused by PCV serotypes from possible hidden carriers.

Probiotics and carriage of Streptococcus pneumoniae serotypes in Danish children, a double-blind randomized controlled trial

“…1 ) and by others 7 , 20 , 22 , 34 . Despite the use of effective vaccines, serotypes 3, 7F and 19A, which are included in PCV13, are still causing IPD among elderly in Denmark 13 , 14 (Fig. 3 ).…”

“…PCV7 includes serotype 4, 6B, 9V, 14, 18C, 19F, and 23F while PCV13 includes the PCV7-serotypes and additional serotypes 1, 3, 5, 6A, 7F, and 19A 1 , 7 . PCV7 led to a significant reduction in IPD caused by PCV7-serotypes markedly among children aged <2 years 1 , 3 , 6 , 13 , but also a significant reduction in IPD cases and carriage of vaccine serotypes among older children and adults was seen, especially in the age group 65+ years 3 , 8 . This phenomenon is known as herd protection 8 .…”

Molecular surveillance on Streptococcus pneumoniae carriage in non-elderly adults; little evidence for pneumococcal circulation independent from the reservoir in children

“…Despite the qPCR-based method being reported as one of the most sensitive for serotype detection in polymicrobial samples 45 , this study demonstrates the need for further expansion of reliable assays. Broader serotype coverage is essential for accurate pneumococcal surveillance in this post-vaccination era, particularly when adult pneumococcal vaccination is considered 46 .…”

The incidence of invasive pneumococcal serotype 3 disease in the Danish population is not reduced by PCV-13 vaccination

“…The focus in recent years has therefore turned to predicting which non-vaccine IPD serotypes will emerge (serotype replacement) and several studies from around the world have shown data on the most common non-PCV serotypes in their region [3, 8]. However, as has also been observed in several studies [13], PCV-13 has not had an equal effect for the thirteen serotypes covered by the vaccine, and in Denmark the current situation is that serotype 3 is still a common cause of IPD in the elderly. On the recent pneumococcal meeting (ISPPD-10) in Glasgow, several countries reported a similar situation, with increasing IPD incidences caused by some of the PCV-13 serotypes in the non-vaccinated age groups, including serotypes 3 and 19A [14, 15, 16, 17].…”