Table 1

Reviewed articles on culture-confirmed influenza in children
Reference Study design Study settings Children age Sample Study qualityaStudy limitations/bias Type of data
Finland
Heikkinen et al., 2004 [35] Prospective, observational study of respiratory infections in community-based children. Community (day care centres, family day care, and schools); 2,231 child-seasons, 1b: prospective cohort study; Resource use, absenteeism
382 episodes of culture-confirmed influenza were documented
Only winter months were evaluated.
Study seasons: 9 October 2000 — 20 May 2001 and 1 October 2001 — 19 May 2002. ≤ 13 years.
Follow-up: not specified.
Heinonen et al., 2010 [42] Randomised, double-blind, controlled trial comparing oseltamivir with placebo for clinical efficacy in children with influenza. Community; 1,185 children were recruited in the community prior to influenza seasons; among those,409 children with fever or respiratory infection who attended the study clinic were randomised to either intervention or placebo; among those,98 (24.7%) children had laboratory-confirmed influenza 1b: randomised, controlled trial; Resource use, absenteeism.
1-3 years
Not a population- based study;b
Broad exclusion criteria prior to enrolment in the trial.
Study seasons: 2 local influenza circulation seasons (14 January — 9 April 2008 and 7 January — 26 March 2009).
Follow-up: 21 days.
France
Ploin et al., 2003 [43] Prospective, observational study in a paediatric ED of a university hospital. Paediatric ED; 304 infants consecutively enrolled during influenza peak 2b: prospective cohort study with poor follow-up; Resource use, absenteeism
≤ 11 months.
99 (33%) with confirmed influenza. Not a population- based study.
Study season: 4 weeks of local influenza epidemic peak (weeks 3-6 in 2002).
Follow-up: 15 days.
Ploin et al., 2007 [36] Prospective, observational study in a paediatric ED of a university hospital. Paediatric ED; 575 children consecutively enrolled during influenza peak 2b: prospective cohort study with poor follow-up; Resource use, absenteeism
< 36 months.
283 (49%) with confirmed influenza. Not a population- based study.
Study season: 4 weeks of local influenza epidemic peak (weeks 3-6 in 2002).
Follow-up: 15 days.
Sanni et al., 2004 [44] Prospective, observational survey of hospitalised children. Hospital; 114 nasal swabs collected; among those – 59 (51.8%) with confirmed influenza. 1b: prospective cohort study; Resource use.
≤ 15 years.
Not a population- based study.
Study season: 37 days of local influenza epidemic (1 January — 6 February 2002).
Follow-up: not specified.
Germany
Ehlken et al., 2005 [45] Cost-of-illness analysis of a prospective, multi-centre, population-based epidemiological study on the impact of LRTI in children. Office-based PCP and hospitals; 3,458 cases with LRTI, including 1,329 office based cases, 2,039 hospitalized cases, and 90 nosocomial cases. 2c: outcomes research; Cost (direct and indirect).c
Not a population- based study;
≤ 36 months.
Limited to children with LRTI;
Costs were imputed based on existing standards.
Study period: 2 years (1 November 1999 — 31 October 2001).
Follow-up: not specified.
Italy
Bosis et al., 2005 [46] Prospective, observational, single-centre study of children enrolled at an ED, comparing the impact of confirmed influenza and RSV with hMPV. ED; All children (n = 1,505) attending the ED on Wednesdays and Sundays. 1b: prospective cohort study; Resource use, absenteeism.
< 15 years.
Not a population- based study.
Of these, 1,019 children had evidence of acute respiratory infection.
Influenza was confirmed by PCR in 230 (15.3%) of total cases; among these, 7 cases were co-infected with RSV or hMPV.
Study season: 5 months (1 November 2002 — 31 March 2003).
Follow-up: not specified.
Esposito et al., 2005 [47] Prospective, observational, single-centre study of children admitted to an ED, comparing the impact of confirmed influenza and RSV. ED; 1,520 children attending ED for acute conditions other than trauma on Wednesdays and Sundays; 1b: prospective cohort study; Resource use, absenteeism
< 15 years.
Not a population- based study.
234 (15.4%) with confirmed influenza.
Study season: 5 months (1 November 2002 — 31 March 2003).
Follow-up: not specified.
Esposito et al., 2011 [37] Prospective, observational study of children presenting to PCP with ILI PCP PCPs continuously followed 21,986 community children 1b: prospective cohort study with good follow-up Resource use, absenteeism, cost (direct and indirect)
< 14 years
6,988 children with ILI presented to PCPs Costs were imputed based on existing standards
Study season: 6 months (1 November 2008 —30 April 2009) 2,143 (30.7%) children had confirmed influenza
Follow-up: not specified
Principi et al., 2003 [48] Prospective, observational, multi-centre study. ED and PCP; 3,771 children with ILI; among those 1b: prospective cohort study; Resource use, absenteeism
< 14 years.
352 (9.3%) with confirmed influenza, including 260 (8.7%) of 2,970 children seen in EDs and 92 (11.5%) of 801 children seen by PCPs Not a population- based study.
Principi et al., 2004 [38] Study season: 6 months (1 November 2001 — 30 April 2002).
Follow-up: not specified.
The Netherlands
Bueving et al., 2004 [49] Randomised, double-blind, placebo-controlled trial comparing inactivated vaccine with placebo for clinical efficacy in children with asthma. Community; 696 children with asthma enrolled through PCP offices prior to influenza seasons’ start. 1b: individual randomised, controlled trial; HRQoL.
6-18 years.
Limited to children with asthma.
Study seasons: 2 influenza seasons (1999 — 2000 and 2000 — 2001).
Follow-up: not specified.
Van Der Zalm, et al., 2009 [50] Prospective birth cohort study, a part of a prospective, ongoing population-based birth cohort study on determinants of wheezing illness. Community; 305 healthy full-term infants (2-3 weeks old); 2b: individual cohort study. Resource use.
≤ 1 year.
668 samples positively tested for any respiratory virus;
18 (2.7%) samples with influenza virus.
Study duration: October 2003 — September 2006.
Follow-up: until infants reached 1 year of age.

ED = emergency department; hMPV human metapneumovirus; HRQoL = health-related quality of life; ILI = influenza-like illness; LRTI = lower respiratory tract infection; PCP = primary care paediatrician; PCR = polymerase chain reaction; RSV = respiratory syncytial virus.

a Study quality according to the Oxford Centre for Evidence-based Medicine scale [41].

b Studies that investigated the impact of influenza at the whole population level rather than the impact in a particular subset of patients (e.g., children admitted to hospital with fever).

c Resource use, absenteeism, and HRQoL also reported but associated with ILI only (not associated with confirmed influenza).

Antonova et al.

Antonova et al. BMC Public Health 2012 12:968   doi:10.1186/1471-2458-12-968

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