Table 1 Pupil attack rates for influenza A(H1N1)pdm09 by grade/age group and sex in a primary school in rural northern Vietnam, January 2010
From: An outbreak of influenza A(H1N1)pdm09 virus in a primary school in Vietnam
Category | N (attack rate %) | Attack rate ratio (95 % CI) | P value |
|---|---|---|---|
Overall attack rate | 103/407 (25.3 %) | – | |
Attack rate by sex | |||
Attack rate in boys | 49/217 (22.6 %) | Reference | |
Attack rate in girls | 54/190 (28.4 %) | 1.36 (0.85–2.18) | 0.18 |
Attack rate by grade | |||
Grade 1 (6 years old) | 37/106 (34.9 %) | 3.30 (1.54–7.15) | 0.001 |
Grade 2 (7 years old) | 15/86 (17.4 %) | 1.30 (0.54–3.14) | 0.53 |
Grade 3 (8 years old) | 13/93 (14.0 %) | Reference | – |
Grade 4 (9 years old) | 27/66 (40.9 %) | 4.26 (1.87–9.85) | <0.001 |
Grade 5 (10 years old) | 11/56 (19.6 %) | 1.50 (0.57–3.95) | 0.36 |