Volume 18, Number 9—September 2012
Dispatch
Demographic Shift of Influenza A(H1N1)pdm09 during and after Pandemic, Rural India
Table 2
Incidence rates for influenza A(H1N1)pdm09 and influenza B among persons with febrile ARI during pandemic and postpandemic periods, by age group, Ballabgarh, India*
Age group, y |
Pandemic period, November 2009–January 2010
|
Postpandemic period, August–October 2010
|
Incidence rate ratio (95% CI) | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Person-years† | Febrile ARI, no. cases | No. tested‡ | No. (%) positive‡ | Incidence (95% CI)§ | Person-years† | Febrile ARI, no. cases | No. tested‡ | No. (%) positive‡ | Incidence (95% CI)§ | |||
Influenza A(H1N1)pdm09 | ||||||||||||
0–5 |
230 | 499 | 411 | 71 (17.3) | 375 (300–463) | 498 | 1,174 | 1,036 | 103 (10.0) | 235 (194–281) | 0.6 (0.5–0.8) ¶ | |
6–18 |
486 | 435 | 281 | 104 (37.0) | 331 (282–386) | 1,061 | 1,245 | 1,012 | 158 (15.6) | 183 (158–210) | 0.6 (0.4–0.7)¶ | |
19–44 |
777 | 362 | 250 | 46 (18.4) | 86 (67–110) | 1,754 | 1,596 | 1,171 | 174 (14.9) | 135 (118–153) | 1.6 (1.2–2.1)# | |
45–59 |
215 | 135 | 93 | 9 (9.7) | 61 (32–104) | 493 | 556 | 413 | 56 (13.6) | 152 (120–191) | 2.5 (1.3–4.9)# | |
>60 |
128 | 84 | 59 | 1 (1.7) | 8 (0.2–44.0) | 294 | 362 | 275 | 15 (5.5) | 68 (42–105) | 8.7 (1.4–360.0)# | |
Influenza B | ||||||||||||
0–5 |
230 | 499 | 411 | 12 (2.9) | 65 (37–108) | 498 | 1,174 | 1,036 | 103 (10.0) | 235 (194–281) | 3.6 (2.1–6.6) | |
6–18 |
486 | 435 | 281 | 15 (5.3) | 47 (30–71) | 1,061 | 1,245 | 1,012 | 138 (13.6) | 160 (137–186) | 3.4 (2.2–5.5) | |
19–44 |
777 | 362 | 250 | 7 (2.8) | 13 (6–24) | 1,754 | 1,596 | 1,171 | 100 (8.5) | 77 (65–92) | 6.0 (3.2–12.8) | |
45–59 |
215 | 135 | 93 | 0 | 0 (0–17) | 493 | 556 | 413 | 19 (4.6) | 53 (34–77) | 0 (0–2.9)** | |
>60 |
128 | 84 | 59 | 0 | 0 (0–29) | 294 | 362 | 275 | 17 (6.2) | 75 (47–113) | 0 (0–2.4)** |
*ARI, acute respiratory infection.
†For surveillance.
‡For influenza.
§Per 1,000 person-years.
¶p<0.0001 (incidence lower in postpandemic than in pandemic period).
#p<0.02 (incidence higher in postpandemic than in pandemic period).
**No influenza B–positive results for these age groups in pandemic period.