Table 2.

Baseline Volunteer Characteristics for Senior and Junior cohorts

Characteristic	SENIOR IM	SENIOR SC	JUNIOR
Number (Percent) Male	13 (50%)	11 (42%)	6 (42%)
Number (Percent) White	25 (96%)	24 (92%)	7 (50%)
Number (Percent) African-American	1 (4%)	2 (8%)	4 (26%)
Median age [range]	73 [65–81]	72 [65–80]	26 [21–34]
Age 65–74 (percent)	20 (77%)	19 (73%)	n/a
Age 75–81 (percent)	6 (23%)	7 (27%)	n/a
Smoker (< 10 cigarettes per day)	0	0	1 (7%)
Median years of education [range]	12 [4–16]	12 [10–18]	16 [14–18]
Alcohol (> 1 can beer, 1 glass wine, or 1 oz. liqueur daily).	0	0	0
Previous influenza or pneumococcal immunization	25 (96%)	25 (96%)	0
Median number of medications [range]	4 [0–8]	3 [0–9]	1 [0–4]
Use of supplemental vitamins	18 (69%)	17 (65%)	5 (36%)
Median co-morbid conditions [range]*	3 [0–7]	3 [0–7]	Not done
Median weight (kg) [range]	79.5 [55–110]	79.5 [53–114]
Median Body Mass Index [range]**	27.7 [22.3–38.6]	29.0 [20.0–41.9]
Median body percentage fat [range]	37.1 [24.5–49.1]	36.9 [20.9–51.4]
Median Charlson Index [range] ***	0 [0–3]	0 [0–3]
Median Mini-Mental Status Exam score+	29 [23–30]	30 [25–30]
Median OARS score [range]#	0 [0–2]	0 [0–0]
Geriatric Depression Scale scores##	0 [0–2]	0 [0–2]

Seniors were randomized to receive the Hepatitis B vaccine by intramuscular (IM) or subcutaneous (SC) administration. Baseline characteristics were similar between Senior IM and SC administration groups. (*) Based on 12 common medical conditions; none = 0, maximum =12. (**) BMI “Normal” =18.5–24.9; “overweight” = 25.1–29.9; “obese” grade 1 = 30–34.9, grade 2 = 35–39.9; grade 3 ≥ 40 [29]. (***) Prognostic 10-year survival for individuals with multiple comorbidities: 0 = 99%; 2 = 90% [30]. (+) Measure of cognitive impairment. Score 24–30 indicates no cognitive impairment [31]. (#) Older Americans Resources and Services, a measure of functional status. Score < 3 = no assistance required for daily activities [32]. (##) Any one symptom of depression; maximum depression score = 15 [33]. n/a = not applicable