Respiratory Viruses Linked to Surge of Invasive Pneumococcal Disease in Children

The spread of respiratory viruses has been linked to a surge in invasive pneumococcal disease (IPD) among young children after COVID-19-related non-pharmaceutical interventions (NPI) were lifted, according to a recent Quebec, Canada-based study published in The Lancet. Beginning in Fall 2021, IPD incidence increased significantly in children aged 5 years and older.

Estimates suggest that respiratory syncytial virus (RSV) dynamics may be responsible for 77% of IPD cases that circulated in children under age 5 in early Fall 2021.

“This unique epidemiological situation, with an RSV outbreak in an unusual moment, without any influenza circulation, and directly followed an IPD surge in young children <5 years, strengthened the link between RSV and IPD dynamics in young children,” wrote study authors in the article.

Before COVID-19, RSV and influenza were believed to trigger IPD based on seasonal patterns. NPIs halted the traditional patterns of respiratory viral circulation, and cases of IPD simultaneously declined. Many were concerned that the post-NPI time would have a surge of circulating viruses, including simultaneous increases in IPD. This study aimed to understand the relationship between respiratory viruses and IPD and evaluate recent changes in rates of IPD by age group.

Investigators used an interrupted time-series approach when looking at data collected between January 2013 and January 2022. The team collected information on 7712 cases of IPD—646 in children younger than age 5 and 3567 in adults aged 65 years and younger.

Findings suggest that IPD activity was temporally associated with circulating RSV in children aged 5 years and younger. Older adults aged 65 years and older did not experience the same incident rate of IPD; however, those who contracted it were more likely to get it from circulating influenza, not RSV, according to the study.

When NPI were implemented in March 2020 because of COVID-19 pandemic restrictions, there were significantly fewer positive tests for respiratory viruses. Beginning in July 2021, NPI were partially lifted and RSV cases had an observable and unusually early spike. For this reason, NPI could be a probable, partial explanation for elevated incidence of IPD.

“Major RSV outbreak can be associated with a surge of IPD cases, as a possible indirect consequence of the respiratory viruses immune debt,” the study authors wrote in the paper.

The study includes some limitations, the first of which being that it is observational and cannot determine causation. Second, it is possible that there are age-specific changes in pneumococcal carriage. Additionally, investigators did not look at rhinovirus or other pathogens, and NPIs varied over time and by age group.

Previous studies identified a positive link between RSV and IPD in young children, whereas RSV and influenza explained IPD infection patterns in older adults. Other studies suggest that RSV was more likely to cause certain, often less invasive disease serotypes.

“In the coming future, the potential benefit of interventions targeting RSV, such as vaccines, for IPD prevention should be considered,” the study authors wrote.

Reference

Ouldali N, Deceuninck G, Lefebvre B, et al. Increase of invasive pneumococcal disease in children temporally associated with RSV outbreak in Quebec: a time-series analysis. News Release. February 14, 2023. Accessed March 6, 2023. doi.org/10.1016/j.lana.2023.100448