- We assessed the seasonality of viral lower respiratory tract infections (V-LRI), bacteremic pneumonia, non-bacteremic pneumonia and non-pneumonia invasive pneumococcal diseases (IPD) in the pre-PCV era. Both bacteremic and non-bacteremic pneumonia seasonality peaked in winter, coinciding with V-LRI seasonality, whereas non-pneumonia IPD peaked in autumn before V-LRI increase, suggesting different pathogenesis. © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: firstname.lastname@example.org.