Pandemic interventions help lessen invasive bacterial infections in children

The implementation of nonpharmaceutical interventions (NPIs) during the COVID-19 pandemic has significantly reduced the incidences of S. pneumoniae and Salmonella spp. among nine major pathogens of invasive bacterial infection (IBI) in children, reports a study.

“This finding suggests that public health measures may attribute to prevention of some IBIs in the paediatric population,” the researchers said.

From January 2018 to December 2020, the researchers performed surveillance for paediatric IBIs caused by nine pathogens (S. pneumoniae, H. influenzae, N. meningitidis, S. agalactiae, S. pyogenes, S. aureus, Salmonella species, L. monocytogenes and E. coli) at 22 hospitals across Korea. They then compared annual incidence before and during the COVID-19 pandemic.

Overall, 651 cases were identified, with annual incidences of 194.0 cases per 100,000 in-patients in 2018, 170.0 in 2019, and 172.4 in 2020. The most common pathogens by age group were as follows: S. agalactiae in infants <3 months (n=129, 46.7 percent), S. aureus in 3 to <24 months (n=35, 37.2 percent), Salmonella spp. in 24 to <60 months (n=24, 34.8 percent), and S. aureus in children ≥5 years (n=128, 60.7 percent). [Pediatr Infect Dis J 2022;41:91-96]

The incidence rate in 2020, as compared to that from 2018 to 2019, dropped by 57 percent for invasive pneumococcal disease (11.5 vs 26.6 per 100,000 in-patients; p=0.014) and 59 percent for Salmonella spp. infection (9.4 vs 22.8 per 100,000 in-patients; p=0.018). On the other hand, significant changes were not observed in invasive infections caused by S. aureus, S. agalactiae, and E. coli.

“The most possible explanation for the differential impact of COVID-19 NPIs on the epidemiology of paediatric IBIs is the difference in the transmission route by organism,” the researchers said. “S. pneumoniae, S. pyogenes, and H. influenzae reside in the respiratory tracts and are mainly transmitted person-to-person through the inhalation of respiratory droplets or close contact.” [J Clin Microbiol 2008;46:225-234; JAMA 1997;277:38-43]

Previous studies suggest that day care attendance and crowding increase the risk for invasive pneumococcal disease in children by facilitating the person-to-person transmission and nasopharyngeal carriage. [BMC Pediatr 2018;18:144; JAMA 1995;273:859-864]

“It is likely that school closure, avoiding attendance to daycare centre, mandatory use of facial masks, and enhanced personal hygiene applied during the COVID-19 pandemic led to substantial decrease in pneumococcal transmission,” the researchers said.

Many countries including South Korea reported a substantial decrease in respiratory viral infection during the COVID-19 pandemic. Decline in viral respiratory tract infections may have contributed to a reduction in pneumococcal infection. [Emerg Infect Dis 2021;27:1685-1688; JAMA Netw Open 2021;4:e2115973]

“However, a decline in Salmonella spp. infection, a nonrespiratory pathogen, is more likely a direct result of NPIs itself through reinforcement of personal hygiene and interruption of movement and person-to-person contact,” the researchers said.

The current study had several limitations. For instance, reduced healthcare-seeking behaviours during the pandemic could have led to the decline in reported IBI cases. It was also not possible to determine whether the decrease in IBIs was the result of fewer bacterial transmission and acquisition or the reduction in various viral respiratory tract infections. Finally, the researchers did not establish serotypes for H. influenzae and S. pneumoniae in this surveillance.