Table 1

Demographic and clinical characteristics of the study population
Characteristics A/H1N1/2009-positive children admitted because of ILI(n=51) A/H1N1/2009-negative children admitted because of ILI(n=221) Healthy controls(n=164)
Males, No. (%) 27 (52.9) 109 (49.3) 85 (51.8)
Caucasians, No. (%) 51 (100.0) 221 (100.0) 164 (100.0)
Mean age ± SD, yrs 3.16 ± 3.46 3.43 ± 3.79 3.39 ± 3.88
Age groups, No. (%)
 <2 years 5 (9.8) 28 (12.7) 15 (9.1)
 2-5 years 44 (86.3) 182 (82.4) 140 (85.4)
 >5 years 2 (3.9) 11 (5.0) 9 (5.5)
Median number of siblings (range) 1 (0–4) 1 (0–3) 1 (0–4)
Exposure to passive smoking, No. (%) 15 (29.4) 69 (31.2) 43 (26.2)
Day care or school attendance, No. (%) 49 (96.1) 210 (95.0) 158 (96.3)
Previous pneumococcal vaccination, No. (%) 46 (90.2) 199 (90.0) 143 (87.2)
Previous pandemic A/H1N1/2009 influenza vaccination, No. (%) 0 (0.0) 3 (1.4) 2 (1.2)
Diagnosis, No. (%)
 Common cold 15 (29.4) 78 (35.2) NA
 Pharyngitis 14 (27.5) 75 (33.9) NA
 Acute otitis media 4 (7.8) 21 (9.5) NA
 Pneumonia 18 (35.4) 47 (21.2) NA
 Minor surgical problem NA NA 164 (100.0)
Hospitalised at enrolment, No. (%) 18 (35.4) 47 (21.2) NA

ILI: influenza-like illness; NA: not applicable; SD: standard deviation. Percentages in parentheses. No significant between-group difference.

Esposito et al.

Esposito et al. Virology Journal 2012 9:270   doi:10.1186/1743-422X-9-270

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