Table 1.
Demographic Characteristics of Patients, by Influenza Vaccination Status and Influenza Virus Status
| Characteristic | Vaccination Status |
Influenza Virus Status |
||||
|---|---|---|---|---|---|---|
| Not Vaccinated (n = 234) | Vaccinated (n = 693) | P values | Negative (N = 841) | Positive (N = 86) | P values | |
| Race | <.001 | .5 | ||||
| White | 62 (144) | 77 (532) | 73 (617) | 69 (59) | ||
| Black | 37 (87) | 22 (149) | 25 (210) | 30 (26) | ||
| Other | 1 (3) | 2 (12) | 2 (14) | 1 (1) | ||
| Age, y | 62.1 (55.7–71.6) | 69.4 (60.8–79.1) | <.001 | 67.8 (59.3–77.6) | 63.9 (56.3–73.6) | .06 |
| Female sex | 62 (146) | 59 (408) | .3 | 59 (499) | 64 (55) | .4 |
| High-risk medical condition | ||||||
| Chronic pulmonary disease | 50 (117) | 55 (383) | .2 | 54 (452) | 56 (48) | .7 |
| Chronic cardiovascular disease | 41 (96) | 51 (351) | .01 | 48 (407) | 46 (40) | .7 |
| Immunosuppressiona | 30 (70) | 33 (231) | .3 | 33 (274) | 31 (27) | .8 |
| Diabetes mellitus | 30 (71) | 37 (257) | .06 | 35 (298) | 35 (30) | .9 |
| Kidney or liver disease | 14 (32) | 18 (126) | .1 | 18 (148) | 12 (10) | .2 |
| Asplenia | 1 (2) | 1 (5) | .8 | 1 (6) | 1 (1) | .6 |
| Current smoking | 31 (72) | 21 (148) | .003 | 23 (193) | 31 (27) | .08 |
| Influenza virus positive | 17 (39) | 7 (47) | <.001 | … | … | |
| Vaccinated | … | … | 77 (646) | 55 (47) | <.001 | |
| ICU admission | 11 (25) | 10 (72) | .9 | 11 (91) | 7 (6) | .3 |
| Death | 1 (2) | 3 (16) | .1 | 3 (17) | 1 (1) | .5 |
| Length of stay, d | 3.0 (2.0–6.0) | 3.0 (2.0–6.0) | .2 | 3.0 (2.0–6.0) | 3.0 (2.0–5.0) | .3 |
| Discharge diagnosisb | .8 | .6 | ||||
| Pneumonia and influenza | 41 (96) | 41 (285) | 41 (345) | 42 (36) | ||
| Other acute respiratory illness | 9 (21) | 8 (57) | 8 (71) | 8 (7) | ||
| Asthma or COPD exacerbation | 26 (61) | 29 (203) | 28 (235) | 34 (29) | ||
| Cardiac disease | 11 (25) | 10 (68) | 10 (88) | 6 (5) | ||
Data are no. (%) of patients or median (interquartile range).
Abbreviation: ICU, intensive care unit.
a Defined as the presence of one of the following: history of transplantation, human immunodeficiency virus infection, and recent or chronic use of steroids, chemotherapy, or use of other immunosuppressive medications.
b Discharge diagnoses were grouped into 5 categories: pneumonia and influenza (International Classification of Diseases, Ninth Revision codes: 480–482, 485–488), other acute respiratory illness (033, 034, 077, 372, 381, 382, 384, 385, 388, 460–466, and 473), chronic obstructive pulmonary disease (COPD) and asthma (490–494 and 496), cardiac disease (410, 411, 413, 428, and 785), and other (any remaining codes).