Volume 17, Number 9—September 2011
Research
Intrahousehold Transmission of Pandemic (H1N1) 2009 Virus, Victoria, Australia
Caroline van Gemert
, Margaret Hellard, Emma S. McBryde, James Fielding, Tim Spelman, Nasra Higgins, Rosemary Lester, Hassan Vally1, and Isabel Bergeri
, Margaret Hellard, Emma S. McBryde, James Fielding, Tim Spelman, Nasra Higgins, Rosemary Lester, Hassan Vally1, and Isabel BergeriTable 4
Secondary attack rates for susceptible household contacts of index case-patients with pandemic (H1N1) 2009, Victoria, Australia, May 18–June 3, 2009*
| Variable | Total no. household contacts | No. with influenza-like illness | Secondary attack rate, % (95% CI) |
|---|---|---|---|
| Individual-level associations | |||
| Sex | |||
| M | 58 | 5 | 8.62 (1.08–14.4) |
| F | 64 | 13 | 20.3 (11.3–32.2) |
| Age, y | |||
| 0–4 | 11 | 1 | 9.09 (0.230–41.3) |
| 5–19 | 35 | 6 | 17.1 (6.50–33.6) |
| 20–49 | 66 | 10 | 15.2 (7.51–26.1) |
| >50 | 10 | 1 | 10.0 (0.25–44.5) |
| Relationship to index case-patient | |||
| Parent/child/partner | 65 | 10 | 15.4 (7.63–26.5) |
| Sibling | 44 | 8 | 18.2 (8.19–32.7) |
| Other family member |
13 |
0 |
0 (0–24.7) |
| Prevention and control measures reported | |||
| Antiviral prophylaxis | 57 | 1 | 1.8 (0.04–9.39) |
| Quarantined >1 d with index case-patient |
73 |
15 |
20.5 (12.0–31.6) |
| Household-level associations | |||
| No. persons | |||
| 2–3 | 7 | 2 | 28.6 (3.67–71.0) |
| 4–5 | 75 | 10 | 13.3 (6.58–23.2) |
| >6 | 40 | 6 | 15.0 (5.71–29.8) |
| No. children | |||
| 1 | 31 | 6 | 19.4 (7.45–37.5) |
| 2 | 47 | 7 | 14.9 (6.20–28.3) |
| >3 | 44 | 5 | 11.4 (3.79–24.6) |
| Cultural and linguistic diversity | |||
| Only English spoken at home | 53 | 5 | 9.4 (3.13–20.7) |
| English and/or other language(s) spoken at home | 69 | 13 | 18.8 (10.4–30.1) |
*CI, confidence interval.
1Current affiliation: La Trobe University, Melbourne, Victoria, Australia.
