Table 5

Number of children, child-months, virus-associated symptomatic and asymptomatic episodes and association between participant characteristics and acute respiratory infections in 151 children

Risk factorChildren (N)Child-months (N)Symptomatic new VDE
OR (95% CI); P value
Asymptomatic new VDE
OR (95% CI); P value
nUnadjustedAdjusted*nUnadjustedAdjusted
Age (months)
  0–<3151423.360Referent rateReferent rate58Referent rateReferent rate
  3–<6142398.092 1.6 (1.2 to2.3);  0.003 1.7 (1.2 to 2.4); 0.003 90 1.7 (1.2, to 2.3); 0.003 1.5 (1.0 to  2.2); 0.03
  6–<12135715.4354 3.5 (2.6 to 4.6); <0.001 3.6 (2.4 to 5.4); <0.001 146 1.5 (1.1 to  2.0); 0.01 1.2 (0.8 to  1.8); 0.46
  12–<241171250.6627 3.5 (2.7 to  4.6); <0.001 3.1 (2.0 to 4.7); <0.001 270 1.6 (1.2 to  2.1); 0.001 1.2 (0.7 to  1.8); 0.54
Sex
  Male741255.1481Referent rateReferent rate262Referent rateReferent rate
  Female771532.26521.1 (1.0 to 1.4), 0.171.1 (0.9 to  1.3); 0.333021.0 (0.8 to 1.2); 0.790.9 (0.7 to  1.2); 0.53
Type of delivery
  Vaginal1031876.3802Referent rateReferent rate387Referent rateReferent rate
  Caesarean48910.93310.8 (0.7 to  1.0); 0.120.8 (0.7 to 1.0); 0.091770.9 (0.7 to 1.2); 0.641.0 (0.8 to  1.3); 0.94
Gestational age at birth
  Term (39w0d–41w6d)1172219.1937Referent rateReferent rate446Referent rateReferent rate
 Late preterm/early term
 (36w0d–38w6d)
34568.11960.8 (0.7 to 1.1); 0.170.9 (0.7 to 1.2); 0.481181.1 (0.8 to  1.5); 0.581.1 (0.8 to  1.5); 0.40
Season
  Summer140678.8196Referent rateReferent rate138Referent rateReferent rate
  Autumn138702.0290 1.4 (1.2 to 1.7); <0.001 1.4 (1.2 to  1.7); <0.001 1350.9 (0.7 to  1.2); 0.641.0 (0.8 to  1.2); 0.75
  Winter138706.6350 1.7 (1.4 to 2.1); <0.001 1.6 (1.3 to  1.9); <0.001 1421.0 (0.8 to 1.3); 0.930.9 (0.7 to  1.2); 0.67
  Spring142699.9297 1.5 (1.2 to 1.8); <0.001 1.4 (1.2 to  1.7); <0.001 1491.1 (0.8 to 1.3); 0.681.1 (0.8 to  1.4); 0.56
Family history
  None present for asthma/eczema731289.6533Referent rateReferent rate286Referent rateReferent rate
  Either parent asthma/eczema751447.35821.0 (0.8 to  1.2); 0.931.0 (0.8 to 1.2); 0.852640.8 (0.7 to  1.1); 0.160.9 (0.7 to  1.1); 0.22
  First-degree relative asthma/eczema†781497.76001.0 (0.8  to 1.2); 0.801.0 (0.8 to  1.2); 0.712780.9 (0.7 to 1.1); 0.220.9 (0.7 to  1.1); 0.36
Tobacco smoke exposure
  No exposure1292383.4973Referent rateReferent rate472Referent rateReferent rate
  Either parent smokes17307.41271.0 (0.7 to  1.4); 0.860.9 (0.6 to 1.1); 0.29751.2 (0.8 to  1.7); 0.421.1 (0.8 to  1.7); 0.51
Household size
  No other children in household991864.9723Referent rateReferent rate350Referent rateReferent rate
  More than one child in household52922.44101.1 (0.9 to 1.4); 0.281.1 (0.9 to  1.4); 0.172141.3 (1.0 to 1.7); 0.051.4 (1.0 to  1.7); 0.04
Maternal education status
  High school14246.71131.1 (0.8 to 1.6); 0.561.0 (0.8 to 1.4); 0.81621.4 (0.9 to  2.1); 0.111.4 (0.9 to  2.1); 0.17
  Diploma/certificate36650.22450.9 (0.7 to  1.1); 0.370.9 (0.7 to 1.1); 0.251491.2 (0.9 to 1.6); 0.291.2 (0.9 to  1.6); 0.15
  University/higher university degree951828.3750Referent rateReferent rate346Referent rateReferent rate
Mode of feeding
  Formula1422281.51039Referent rateReferent rate484Referent rateReferent rate
  Breastmilk145505.594 0.4 (0.3 to  0.5); <0.001 1.2 (0.9 to 1.7); 0.2880 0.7 (0.6 to  0.9); 0.01 0.9 (0.6 to  1.3); 0.47
Childcare attendance
  No childcare1501423.6423Referent rateReferent rate242Referent rateReferent rate
  Informal childcare only47389.51171.2 (0.9 to 1.5); 0.130.8 (0.6 to 1.1); 0.16931.3 (1.0 to 1.7); 0.101.3 (0.9 to  1.7); 0.16
  Formal and/or informal childcare90973.8593 2.2 (1.9 to  2.5); <0.001 1.5 (1.3 to 1.9); <0.001 229 1.4 (1.1 to  1.7); 0.002 1.4 (1.0 to  1.8); 0.03
  • Statistically significant risk ratios and attributable fractions have been highlighted in bold.

  • *Adjusted for age, sex, type of delivery, gestational age, season, family history, tobacco smoke exposure, household size, maternal education status, mode of feeding and childcare attendance.

  • †Mother, father or sibling.

  • OR, odds ratio; VDE, virus detection episode.