The Pneumococcus–Respiratory Virus Connection—Unexpected Lessons From the COVID-19 Pandemic

Abstract

Streptococcus pneumoniae is a leading cause of acute respiratory infection and invasive disease in all ages. Nasopharyngeal carriage is a necessary step preceding any pneumococcal disease. However, S pneumoniae is also a normal part of the microbiome of the upper respiratory tract in early childhood, and children constantly acquire and clear carriage, mostly without incident. This apparent paradox suggests that other factors beyond nasopharyngeal carriage play an important role in the pathogenesis of pneumococcal disease. 1 Epidemiological, clinical, and experimental evidence suggests that certain respiratory viruses may have a substantial role in the burden of pneumococcal disease. [1][2][3][4] However, most of the evidence for either coinfections or virus-induced pneumococcal secondary infections in children has been derived from observational epidemiological studies reporting association, which does not demonstrate a causative relationship.

The COVID-19 pandemic as an opportunity for unravelling the causative association between respiratory viruses and pneumococcus-associated disease in young children: a prospective study

“…Shortly after the emergence of the COVID-19 pandemic, temporary elimination of the circulation of RSV, hMPV, flu, and PIV occurred globally, while RhV and AdV continued to circulate. 13 , 16 At the same time, a drop in pneumococcal disease rates was seen. 17 , 18 , 19 , 20 , 21 This was initially believed to result from reduced pneumococcal circulation, caused by the mitigation measures adopted during the COVID-19 pandemic.…”

“…However, nasopharyngeal carriage rates of pneumococcus among young children were largely unchanged during the pandemic, suggesting that this was not the main factor behind the decline in rates of pneumococcal disease. 12 , 13 , 16 , 22 An alternative possibility, based on previous observations of bacterial-viral coinfections, is that the dramatic suppression of the respiratory viruses led to the decline in rates of IPD.…”

The COVID-19 Pandemic as an Opportunity for Unravelling the Causative Association between Respiratory Viruses and Pneumococcus-Associated Disease in Young Children: A Prospective Study

“…However, nasopharyngeal carriage rates of pneumococcus among young children were largely unchanged during the pandemic, suggesting that this was not the main factor behind the decline in IPD. 8, 13, 16, 22 An alternative possibility, based on previous observations of bacterial-viral coinfections, is that the dramatic suppression of the respiratory viruses led to the decline in rates of IPD.…”

“…Shortly after the emergence of the COVID-19 pandemic, temporary elimination of the circulation of RSV, hMPV, flu, and PIV occurred globally, while RhV and AdV continued to circulate. 13,16 At the same time, a drop in pneumococcal disease rates was seen, [17][18][19][20][21] initially believed to result from reduced pneumococcal circulation, caused by the mitigation measures adopted during the COVID-19 pandemic.…”

“…Shortly after the emergence of the COVID-19 pandemic, temporary elimination of the circulation of RSV, hMPV, flu, and PIV occurred globally, while RhV and AdV continued to circulate. 13, 16 At the same time, a drop in pneumococcal disease rates was seen, 17-21 initially believed to result from reduced pneumococcal circulation, caused by the mitigation measures adopted during the COVID-19 pandemic. However, nasopharyngeal carriage rates of pneumococcus among young children were largely unchanged during the pandemic, suggesting that this was not the main factor behind the decline in IPD.…”