Table 2 Incidence of CHIKF among children < 16 years in Ngerenya and Pingilikani
From: Endemic chikungunya fever in Kenyan children: a prospective cohort study
|  | Ngerenya (N = 73,028 pyo) | Pingilikani (N = 63,481 pyo) | ||
|---|---|---|---|---|
| Â | Incidence (95% CI) | IRRs (95% CI) | Incidence (95% CI) | IRRs (95% CI) |
Overall incidence | 336 (296,381) | – | 288 (248,333) | – |
Year | ||||
 2014 | – | – | 536 (418,676) | Ref |
 2015 | 79 (41,138) | Ref | 348 (255,464) | 0.65 (0.45, 0.94) |
 2016 | 920 (774,1086) | 11.58 (6.42, 20.89) | 274 (192,380) | 0.51 (0.34, 0.77) |
 2017 | 514 (406,642) | 6.47 (3.52, 11.88) | 122 (69,198) | 0.23 (0.13, 0.39) |
 2018 | 127 (72,207) | 1.60 (0.76, 3.39) | 129 (70,216) | 0.24 (0.14, 0.43) |
Sex | ||||
 Female | 320 (265,384) | Ref | 331 (270,401) | Ref |
 Male | 352 (294,418) | 1.10 (0.86, 1.41) | 245 (194,306) | 0.74 (0.55, 0.99) |
Age (years) | ||||
 < 1 | 1363 (1030,1770) | Ref | 979 (674,1375) | Ref |
 1 to < 5 | 658 (549,783) | 0.48 (0.35, 0.66) | 509 (406,629) | 0.52 (0.35, 0.78) |
 5 to < 10 | 221 (166,288) | 0.16 (0.11, 0.24) | 208 (151,280) | 0.21 (0.14, 0.33) |
 10 to 15 | 35 (16,67) | 0.03 (0.01, 0.05) | 93 (58,143) | 0.10 (0.06, 0.17) |
Distance from dispensary (Km) | ||||
 < 1 | 881 (599,1251) | Ref | 1037 (677,1519) | Ref |
 1 to < 2 | 636 (483,822) | 0.72 (0.47, 1.12) | 855 (605,1173) | 0.82 (0.50, 1.36) |
 2 to < 3 | 456 (353,580) | 0.52 (0.34, 0.79) | 883 (700,1099) | 0.85 (0.55, 1.33) |
 3 to < 4 | 376 (277,498) | 0.43 (0.27, 0.67) | 207 (116,343) | 0.20 (0.11, 0.38) |
 4 to < 5 | 181 (120,261) | 0.21 (0.12, 0.34) | 148 (81,249) | 0.14 (0.07, 0.27) |
 5 to < 6 | 84 (47,139) | 0.10 (0.05, 0.18) | 32 (15,59) | 0.03 (0.02, 0.06) |
Season | ||||
 Jan - Mar | 459 (368,566) | Ref | 273 (199,365) | Ref |
 Apr - Jun | 350 (271,445) | 0.76 (0.55, 1.05) | 433 (338,546) | 1.59 (1.09, 2.30) |
 Jul - Sep | 276 (206,362) | 0.60 (0.43, 0.85) | 281 (205,374) | 1.03 (0.68, 1.55) |
 Oct - Dec | 249 (179,338) | 0.54 (0.37, 0.79) | 147 (91,225) | 0.54 (0.32, 0.91) |