Table 2.
Estimates of Incidence Among Outpatients and Inpatients With Community-acquired Norovirus Infection at 4 Veterans Affairs Medical Centers, November 2011–September 2015
| Outpatient | Inpatient Community-acquired | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Characteristic | Total Annual Unique Patients Served, No. | Outpatient AGE Encounters, No. | No. of Stool Specimens Collected (% of AGE Encounters) | No. Norovirus-positive (%) | Norovirus Incidence per 100 000 Patient-years (95% CI) | Inpatient AGE Discharges | No. of Stool Specimens Collected (% of AGE Discharges) | No. Norovirus Positive (%) | Norovirus Incidence per 100 000 Patient-years (95% CI) |
| Site | |||||||||
| Bronx | 97 754 | 4826 | 166 (3.4) | 15 (9.0) | 446 (238–654) | 683 | 244 (35.7) | 10 (4.1) | 29 (11–49) |
| Houston | 384 772 | 12 963 | 224 (1.7) | 22 (9.8) | 331 (196–466) | 2225 | 164 (7.4) | 16 (9.8) | 56 (28–85) |
| Los Angeles | 253 189 | 8356 | 152 (1.8) | 4 (2.6) | 87 (22–174) | 719 | 115 (16.0) | 12 (10.4) | 30 (15–49) |
| Atlanta | 366 961 | 12 178 | 246 (2.0) | 16 (6.5) | 216 (121–324) | 1839 | 292 (15.9) | 8 (2.7) | 14 (5–24) |
| Age category, y | |||||||||
| 18–44 | 209 904 | 8069 | 174 (2.2) | 14 (8.0) | 309 (155–486) | 508 | 82 (16.1) | 7 (8.5) | 21 (9–35) |
| 45–64 | 410 409 | 15 769 | 313 (2.0) | 30 (9.6) | 368 (246–491) | 2388 | 391 (16.4) | 12 (3.1) | 18 (9–30) |
| 65–84 | 416 835 | 12 408 | 268 (2.2) | 11 (4.1) | 122 (56–200) | 2178 | 288 (13.2) | 21 (7.3) | 38 (24–54) |
| ≥85 | 65 528 | 2077 | 32 (1.5) | 2 (6.3) | 198 (0–495) | 392 | 51 (13.0) | 6 (11.8) | 70 (23–129) |
| Surveillance year | |||||||||
| 2011–2012 | 279 152 | 7983 | 161 (2.0) | 14 (8.7) | 239 (124–382) | 1298 | 249 (28.9) | 21 (8.4) | 38 (24–54) |
| 2012–2013a | 208 003 | 7364 | 190 (2.6) | 12 (6.3) | 234 (130–354) | 1141 | 173 (15.2) | 6 (3.5) | 19 (6–35) |
| 2013–2014 | 303 630 | 11 462 | 233 (2.0) | 24 (10.3) | 389 (243–535) | 1516 | 239 (15.7) | 13 (5.4) | 28 (15–42) |
| 2014–2015 | 311 891 | 11 514 | 204 (1.8) | 7 (3.4) | 129 (36–217) | 1511 | 154 (10.1) | 6 (3.9) | 19 (6–35) |
| Total | 1 102 676 | 38 323 | 788 (2.1) | 57 (7.2) | 252 (194–313) | 5466 | 815 (14.9) | 46 (5.6) | 28 (20–36) |
Abbreviations: AGE, acute gastroenteritis; CI, confidence interval.
aData from Los Angeles for 2012–2013 were not available.