title: Influenza and RSV make a modest contribution to invasive pneumococcal disease incidence in the UK.
abstract: OBJECTIVE
  The common seasonality of incidence of invasive pneumococcal disease (IPD) and viral respiratory infections has long been recognized, however, the extent to which this affects the association between the pathogens is unknown. We have analysed weekly surveillance data of IPD, influenza and respiratory syncytial virus (RSV), using ambient temperature and hours of sunshine as measures of seasonality.
  
  
  METHODS
  Reported cases of influenza, IPD and RSV, were collected in England and Wales, from week 1 (January) 1996 to week 23 (June) 2009. The associations between IPD and respiratory viral infections were analysed using several statistical methods, including correlation coefficients and both additive and multiplicative regression models.
  
  
  RESULTS
  6-7.5% of cases of IPD are attributable to influenza and 3-4% attributable to RSV. Correlation coefficients reported considerably stronger associations between IPD and the viral infections compared to regression models.
  
  
  CONCLUSIONS
  A small but potentially important percentage of IPD may be attributable to influenza and RSV when adjusted for seasonality by temperature. Jointly these viral infections may lead to over 10% of IPD cases. Therefore, prevention of viral respiratory infections may offer some additional benefit in reducing invasive pneumococcal infections.
authors.affiliation: School of Social and Community Medicine, University of Bristol, Canynge Hall, 39 Whatley Road, Bristol BS8 2PS, UK. E.Nicoli@bristol.ac.uk
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Nicoli
authors.forename: Caroline L
authors.initials: CL
authors.lastname: Trotter
authors.forename: Katherine M E
authors.initials: KM
authors.lastname: Turner
authors.forename: Caroline
authors.initials: C
authors.lastname: Colijn
authors.forename: Pauline
authors.initials: P
authors.lastname: Waight
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Miller
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004739:England / Q000453:epidemiology; D062665:Epidemiological Monitoring; D006801:Humans; D015994:Incidence; D007223:Infant; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000821:virology; D012044:Regression Analysis; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology* / Q000821:virology; D012621:Seasons; D018709:Statistics, Nonparametric; D014852:Wales / Q000453:epidemiology