The aim of this study was to assess the co-seasonality and co-detection of respiratory viral infections and bacteraemia in children since the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13).
Children <18 years were eligible for inclusion if they had a respiratory infection and a positive PCR-based assay for respiratory viruses as well as a positive blood culture from 2010 to 2018 at a single referral centre in the United States regardless of their underlying medical condition or antibiotic treatment history. Monthly incidence rates of respiratory viruses and bacteraemia were analysed with a seasonal-trend decomposition procedure based on loess (STL) and cross-correlation functions using time series regression modelling.
We identified 7,415 unique positive respiratory virus tests, including 2,278 RSV (31%), 1,825 influenza viruses (24%), 1,036 parainfluenza viruses (14%), 1,017 hMPV (14%), 677 seasonal coronaviruses (9%), and 582 adenoviruses (8%), and a total of 11,827 episodes of bacteraemia. Significant co-seasonality was found between all-cause bacteraemia and RSV (OR=1.76, 95% CI 1.50-2.06, P<0.001), influenza viruses (OR=1.38, 95% CI 1.13-1.68, P=0.002), and seasonal coronaviruses (OR=1.18, 95% CI 1.09-1.28, P<0.001), respectively. Analysis of linked viral-bacterial infections in individual children indicated that the rate ratio (RR) of bacteraemia associated with hMPV (RR=2.73, 95% CI 1.12-6.85, P=0.019) and influenza (RR=2.61, 95% CI 1.21-6.11, P=0.013) were more than double that of RSV. Staphylococcus aureus and Streptococcus pneumoniae were the most commonly identified pathogens causing bacteraemia.
There is a significant association between hMPV and influenza viruses, and bacteraemia of all causes in hospitalised children at a single paediatric centre in the United States. Large multicentre studies are needed to confirm these findings and to elucidate the mechanisms by which hMPV potentiates the virulence and invasive capacity of diverse bacteria.

Copyright © 2020 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.