Table 5 Results from household-level multivariable regression analyses using Poisson mixed-effects models examining the association between having a coinfected (versus singly infected) index case within the household and the incidence of virus transmission

From: The role of viral interaction in household transmission of symptomatic influenza and respiratory syncytial virus

Characteristic

IRR (95% CI)

z value

P value

Influenza A virus modela

Coinfected index case

0.44 (0.29–0.66)

−3.895

9.81e-05

No. household members

0.91 (0.76–1.10)

−0.942

0.346

Index case <18

2.13 (1.46–3.10)

3.934

8.37e-05

Influenza B virus modelb

Coinfected index case

0.85 (0.39–1.84)

−0.423

0.672

No. household members

1.29 (0.94–1.78)

1.573

0.116

Index case <18

1.07 (0.47–2.42)

0.166

0.868

Respiratory syncytial virus modelc

Coinfected index case

0.51 (0.30–0.86)

−2.548

0.011

No. household members

1.03 (0.81–1.32)

0.249

0.803

Index case <18

1.24 (0.64–2.42)

0.636

0.525

  1. In the influenza A virus analysis, there were 151 households with coinfected index cases and 395 with singly infected index cases. In the influenza B virus analysis, there were 54 households with coinfected index cases and 177 with singly infected index cases. In the respiratory syncytial virus analysis, there were 147 households with coinfected index cases and 223 with singly infected index cases. P values were computed using two-sided asymptotic Wald tests.
  2. aIntraclass Correlation Coefficient (ICC) = 0.187, R2 (conditional) = 0.223, R2 (marginal) = 0.044,
  3. N = 546 household illness events.
  4. bICC = 0.248, R2 (conditional) = 0.258, R2 (marginal) = 0.013, N = 231 household illness events.
  5. cICC = 0.267, R2 (conditional) = 0.280, R2 (marginal) = 0.018, N = 370 household illness events.
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