TABLE 1—

Geometric Mean Concentrations (GMCs) of Antibodies Specific to Hepatitis A Virus (Anti-HAV) and Hepatitis B Surface Antigen (Anti-HBs,) and Percentage of Personnel Protected Over Time After Entry Into Military Service: United States, 2006–2010

	Anti-HAV			Anti-HBs
Days^a	Total No.^b	GMC^c	% Protected	Total No.^b	GMC^c	% Protected
Baseline	426	2.1	14	407	21.0	57
31–60	91	6.9	37	90	139.4	67
61–90	53	17.8	57	52	1471.6	87
91–120	71	35.0	69	71	1197.7	89
121–150	63	25.8	68	62	1477.4	92
151–180	31	38.0	74	29	1157.0	90
181–210	24	31.0	79	23	642.5	83
211–240	22	23.1	64	22	1055.0	100
241–270	17	20.6	71	17	293.3	82
271–300	13	14.5	54	14	417.2	79
301–330	15	4.7	47	14	489.2	93
331–360	20	14.2	55	20	453.3	85

^{^a}

Days at which serum samples were collected relative to military service entry. Serum samples were obtained from the Department of Defense Serum Repository as part of routine surveillance.

^{^b}

Number may vary from the total number of participants in a group or day range because of the sampling process.

^{^c}

GMC of serum antibodies as measured in mIU/mL at the Centers for Disease Control and Prevention by using the ETI-AB-HAVK PLUS enzyme immunoassay diagnostic kit (DiaSorin, Saluggia, Italy), which includes a high positive control, containing 1200–2000 mIU/mL anti-HAV (World Health Organization second International Standard, 1998) and the VITROS ECi Immunodiagnostic System for anti-HBs (Ortho Clinical Diagnostics, Inc., Raritan, NJ, USA). Anti-HBs levels ≥ 10 mIU/mL indicated seroprotection and a similar level was considered seroprotective for anti-HAV. SPSS version 23.0 (IBM Corp., Armonk, NY, USA) was used to calculate two-way ANOVA comparisons, GMCs, and percentages at or above seroprotective levels.