Roxanne E. Williams, MD MPH Hepatitis B Vaccination Coverage among Students at a US Health Science Graduate School Roxanne E. Williams, MD MPH Good Morning, I’m Roxanne Williams, an Epidemic Intelligence Officer in the Division of Viral Hepatitis at the Centers of Disease Control in Atlanta, GA. Thank you for the opportunity to discuss our study on hepatitis B Vaccination Coverage among students at a US health science graduate school Epidemic Intelligence Service Officer National Immunization Conference March 30, 2011 National Center for HIV/AIDS, Viral Hepatitis, STD , and TB Prevention Division of Viral Hepatitis

Outline Hepatitis B Virus Infection & Vaccine in Healthcare Workers Study Rationale & Objectives Methods Results Limitations Conclusions In doing so, I will Provide brief background on Hepatitis B infection and vaccination in HCWs Discuss our study rationale and objectives And review study methods, results, limitations, conclusions

Hepatitis B Virus in Healthcare Workers Hepatitis B virus (HBV) is a DNA virus that infects the liver HBV is transmitted primarily through percutaneous and mucosal exposure to blood HBV is the most common blood-born pathogen posing occupational risk to healthcare workers(HCW)* HCW risk is related to degree of contact with blood in workplace Before introduction of the hepatitis B vaccine, HBV infection prevalence among HCW was ~10 times higher than the general population Hepatitis B is caused by a DNA virus that infects the liver It is primarily transmitted primarily through percutaneous and mucosal exposure to blood Hepatitis B virus (or HBV) is the most common blood-born pathogen that poses an occupational risk to healthcare workers. - HCWs risk is primarily related to the degree of contact with blood in the work place -Before introduction of the hepatitis B vaccine, HBV infection prevalence among HCW was ~10 times higher than the general population }}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}} Ciorlia LAS, Zanetta DMT. Hepatitis B in Healthcare Workers: Prevalence, Vaccination and Relation to Occupational Facters. Brazilian Journ of Inf Ds. 2005; 9 (5):384-389*http://www.who.int/mediacentre/factsheets/fs204/en/ **Kim, W.R. et.al Hepatology 2009 * J Glob Infect Dis,2010 **CDC, MMWR 2001 & 2006

Hepatitis B Vaccine Hepatitis B vaccine is the most effective means of prevention Vaccine is well established as a safe and highly effective 3-dose primary series Hepatitis B vaccination of healthcare workers (HCW) recommended in 1982 Vaccine-induced immunity is assessed by measurement of antibodies against Hepatitis B surface antigen (anti-HBs A level of anti-HBs ≥ 10 IU/L after completing the primary series is associated with protection 1990s – Postvaccination testing recommended for HCWs Hepatitis B vaccine is the most effective means of prevention It is well established AS A safe and highly effective vaccine since its introduction in 1981 and is delivered in a 3 doses primary series. Because of the high risk of HBV infection among HCWs, CDC and ACIP recommended routine pre-exposure vaccination in 1982. Vaccine induced immunity is assessed through measurement of antibodies against hepatitis B surface antigen, hereafter referred to as anti-HBs An Antibody level greater than or equal to 10 international units per liter following the hepatitis B primary vaccination series is associated with protection. In the 1990s, CDC and ACIP recommended postvaccination testing for HCWs.

Study Rationale Healthcare students are exposed to blood and blood products and thus also at increased risk of exposure to HBV Little information currently available on Hepatitis B vaccine coverage among healthcare students in the US There is interest in persistence of protection provided by vaccine since hepatitis B antibody levels decline over time What are vaccine coverage and antibody levels among healthcare students? ENTER Healthcare students are exposed to blood and blood products and thus also at increased risk of exposure to HBV However, there is little information available regarding hepatitis B vaccination coverage among healthcare students in the US. Since the vaccine’s introduction, there has been interest in persistence of seroprotection provided by the vaccine since hepatitis B antibody levels decline over time So, What is vaccine coverage and antibody levels among healthcare students?

Objectives Primary Objectives Secondary Objectives To determine vaccination coverage and anti-HBs levels among a cohort of US healthcare students Secondary Objectives To determine persistence of adequate anti-HBs levels among those who completed the primary series To evaluate response to booster doses of vaccine Our primary objective address sought to address this. Our chief aim was to determine vaccination coverage and antiHBs levels among a cohort of US health care students ENTER Our secondary objectives were - To determine persistence of adequate anti-HBs levels among those who completed the primary series - and, to evaluate the response to booster doses of vaccine

Methods – Design, Setting, Eligibility Retrospective cohort study in December 2009 Study setting: Midwestern University (MWU) Private, graduate school in Illinois Programs in osteopathic medicine, dentistry, and allied health Eligibility Criteria Health science MWU students who matriculated from 2004-2009 and had a student health clinic record A retrospective cohort study was conducted in december 2009 at Midwestern University: a private, graduate school in IL, offering programs in the health sciences including osteopathic medicine, dentistry, and allied health ENTER (Physician assistant, physical therapy, occupational therapy, biomedical sciences, clinical psychology, doctor of health sciences) Eligible participants were Health science students of Midwestern University who matriculated from 2004-2009 and had a student health clinic vaccination record

Methods – Data Collection Data collected through abstraction of student medical records Demographic information (date of birth, gender, birthplace, ethnicity) Dates of Hepatitis B vaccine doses All postvaccination anti-HBs values with dates Hepatitis B surface antigen status Data was collected through abstraction of student medical records to obtain variables of interest (namely): Demographic information (date of birth, gender, birthplace, ethnicity) Dates of hepatitis B vaccine doses All postvaccination anti-HBs values with dates and Hepatitis B surface antigen status

Statistical Methods Percentage vaccine coverage was compared between students who received ≤3 doses versus 3 doses of vaccine by chi-square test Association of antibody levels to student characteristics, age at vaccination, time between primary series and postvaccination testing were assessed by t-test and chi-square test Percentage vaccine coverage was compared among students who received <3 doses and those who received 3 doses of vaccine by chi-square testing Association of antibody levels to student characteristics, age at vaccination, time between primary series and postvaccination testing were assessed by t-test and chi-square test

Study Population & Completeness of Vaccination Records health science students matriculated 2004-2009 & had health clinic record Missing critical data (802) Chronic HBV (6) Allergy to vaccine (1) N=2643 (76.6%) received ≤3 doses & had anti-HBs values ENTER Of 3542 who matriculated from 2004-2009, all had health clinic records and thus all were eligible to participate 809 were excluded due to absence of critical data, chronic HBV infection or allergy to vaccination The remaining 2643 were those who received less than or equal to 3 doses in their primary series and had documented post vaccination anti-HBS values 2481 (or 71% of eligible participants) completed the primary series. N=2481 (71.9%) received 3 doses

Proportion of students with anti-HBs ≥10 IU/L, by number of vaccine doses Number of students Percentage Post vaccination antiHBs values were compared between students by number of vaccines doses received. These groups are listed along the X axis and precentage of students along the y axis. The left most bar represents all 2643 students who received less than or equal to 3 vaccinations. 2464 ( or 93%), had acceptable antiHBs levels (meaning levels ≥ 10). The right bar represents the 2481 students who completed the primary series, of these students 94% of students who completed the series had acceptable anti-HBs levels.

Characteristics of students with postvaccination serology, by anti-HBs level (N=2643) Total N (%) Anti –HBs <10 IU/L N (%) Anti -HBs ≥10 IU/L N (%) OR CI Gender Female 1698 (64.0) 134 (7.9) 1564 (92.1) Ref Male 945 (36.0) 80 (8.5) 865 (91.5) 1.07 0.8-1.4 Country of birth* US 1614 (85.4) 132 (8.2) 1482 (91.8) Other 276 (14.6) 28 (10.1) 248 (89.9) 1.3 0.8-1.9 Median age at start of primary series (years) 14.7 Range (0-49) 16.5 Range (0-48.8) 15.7 0.10* The next 3 tables describe characteristics of the students who received less than or equal to 3 doses AND had postvaccination serology ENTER Ref = reference group *t-test

Characteristics of students with postvaccination serology, by anti-HBs level (N=2643) Total N (%) Anti –HBs <10 IU/L N (%) Anti -HBs ≥10 IU/L N (%) OR CI Gender Female 1698 (64.0) 134 (7.9) 1564 (92.1) Ref Male 945 (36.0) 80 (8.5) 865 (91.5) 1.07 0.8-1.4 Country of birth* US 1614 (85.4) 132 (8.2) 1482 (91.8) Other 276 (14.6) 28 (10.1) 248 (89.9) 1.3 0.8-1.9 Median age at start of primary series (years) 14.7 Range (0-49) 16.5 Range (0-48.8) 15.7 0.10* 1. The majority (or 64%) of students were female. Among both males and females, ~90% had anti-HBs suggestive of immunity ENTER Ref = reference group *t-test

Characteristics of students with postvaccination serology, by anti-HBs level (N=2643) Total N (%) Anti –HBs <10 IU/L N (%) Anti -HBs ≥10 IU/L N (%) OR CI Gender Female 1698 (64.0) 134 (7.9) 1564 (92.1) Ref Male 945 (36.0) 80 (8.5) 865 (91.5) 1.07 0.8-1.4 Country of birth* US 1614 (85.4) 132 (8.2) 1482 (91.8) Other 276 (14.6) 28 (10.1) 248 (89.9) 1.3 0.8-1.9 Median age at start of primary series (years) 14.7 Range (0-49) 16.5 Range (0-48.8) 15.7 0.10* 85% of students were US born. Both foreign born and US born students groups, ~ 90% had levels greater than or equal to 10. ENTER Ref = reference group *t-test

Characteristics of students with postvaccination serology, by anti-HBs level (N=2643) Total N (%) Anti –HBs <10 IU/L N (%) Anti -HBs ≥10 IU/L N (%) OR CI Gender Female 1698 (64.0) 134 (7.9) 1564 (92.1) Ref Male 945 (36.0) 80 (8.5) 865 (91.5) 1.07 0.8-1.4 Country of birth* US 1614 (85.4) 132 (8.2) 1482 (91.8) Other 276 (14.6) 28 (10.1) 248 (89.9) 1.3 0.8-1.9 Median age at start of primary series (years) 14.7 Range (0-49) 16.5 Range (0-48.8) 15.7 0.10* Median age at the start of the primary series was ~ 15 years of age. Gender, country of birth, and median age were NOT associated with anti-HBs levels. Ref = reference group *t-test

Characteristics of students with postvaccination serology, by anti-HBs level (N=2643) Total N (%) Anti –HBs <10 IU/L N (%) Anti -HBs ≥10 IU/L N (%) OR CI Race/Ethnicity White, Non-Hispanic 1659 (62.8) 128 (7.7) 1531 (92.3) Ref Black, Non-Hispanic 31 (1.2) 5 (16.1) 26 (83.9) 2.3 0.8-6.1 Asian/Pacific Islander 448 (17) 38 (8.5) 410 (91.5) 1.1 0.8-1.6 Hispanic 48 (1.8) 6 (12.5) 42 (87.5) 1.7 0.7-4.1 American Indian/ Alaska Native 2 (0.1) (0) (100) und Other/Unknown 455 (17.2) 37 (8.1) 418 (91.9) 0.7-1.6 ENTER Ref = reference group Und = undefined

Characteristics of students with postvaccination serology, by anti-HBs level (N=2643) Total N (%) Anti –HBs <10 IU/L N (%) Anti -HBs ≥10 IU/L N (%) OR CI Race/Ethnicity White, Non-Hispanic 1659 (62.8) 128 (7.7) 1531 (92.3) Ref Black, Non-Hispanic 31 (1.2) 5 (16.1) 26 (83.9) 2.3 0.8-6.1 Asian/Pacific Islander 448 (17) 38 (8.5) 410 (91.5) 1.1 0.8-1.6 Hispanic 48 (1.8) 6 (12.5) 42 (87.5) 1.7 0.7-4.1 American Indian/ Alaska Native 2 (0.1) (0) (100) und Other/Unknown 455 (17.2) 37 (8.1) 418 (91.9) 0.7-1.6 Approximate 63% of students were white, 1.2 % black, 17% asian/pacific islander, 2% hispanic and less than 1 % american indian/alaska native. Ref = reference group Und = undefined

Characteristics of students with postvaccination serology, by anti-HBs level (N=2643) Total N (%) Anti –HBs <10 IU/L N (%) Anti -HBs ≥10 IU/L N (%) OR CI Race/Ethnicity White, Non-Hispanic 1659 (62.8) 128 (7.7) 1531 (92.3) Ref Black, Non-Hispanic 31 (1.2) 5 (16.1) 26 (83.9) 2.3 0.8-6.1 Asian/Pacific Islander 448 (17) 38 (8.5) 410 (91.5) 1.1 0.8-1.6 Hispanic 48 (1.8) 6 (12.5) 42 (87.5) 1.7 0.7-4.1 American Indian/ Alaska Native 2 (0.1) (0) (100) und Other/Unknown 455 (17.2) 37 (8.1) 418 (91.9) 0.7-1.6 A greater proportion of Blacks, Hispanics students had anti-HBs values under 10, though the difference was not statistically significant Ref = reference group Und = undefined

Interval from primary vaccine series to postvaccination testing among students who received 3 doses of vaccine (N=2481) Interval (Years) Total N (%) Anti -HBs <10IU/L N (%) Anti -HBs ≥ 10 IU/L N (%) Odds Ratio Confidence Interval < 5 855 (34.5) 32 (3.7) 823 (96.3) Ref 5-10 931 (37.5) 81 (8.7) 850 (91.3) 2.45 1.6-3.7 11-15 634 (25.6) 57 (9.0) 577 (91.0) 2.54 ≥ 16 61 (2.5) 5 (8.2) 56 (91.8) 2.30 0.9-6.1 Time interval from end of primary series to date of post vaccination testing was analyzed. This interval was categorized as shown here, but ranged from 0 to 24 years. Ref= reference group

Interval from primary vaccine series to postvaccination testing among students who received 3 doses of vaccine (N=2481) Interval (Years) Total N (%) Anti -HBs <10IU/L N (%) Anti -HBs ≥ 10 IU/L N (%) Odds Ratio Confidence Interval < 5 855 (34.5) 32 (3.7) 823 (96.3) Ref 5-10 931 (37.5) 81 (8.7) 850 (91.3) 2.45 1.6-3.7 11-15 634 (25.6) 57 (9.0) 577 (91.0) 2.54 ≥ 16 61 (2.5) 5 (8.2) 56 (91.8) 2.30 0.9-6.1 Most students had post vaccination testing done within 5-10 years of completing their primary series. Ref= reference group

Interval from primary vaccine series to postvaccination testing among students who received 3 doses of vaccine (N=2481) Interval (Years) Total N (%) Anti -HBs <10IU/L N (%) Anti -HBs ≥ 10 IU/L N (%) Odds Ratio Confidence Interval < 5 855 (34.5) 32 (3.7) 823 (96.3) Ref 5-10 931 (37.5) 81 (8.7) 850 (91.3) 2.45 1.6-3.7 11-15 634 (25.6) 57 (9.0) 577 (91.0) 2.54 ≥ 16 61 (2.5) 5 (8.2) 56 (91.8) 2.30 0.9-6.1 2.5 % had postvaccination testing done 16 years or more after completing primary series. Ref= reference group

Interval from primary vaccine series to postvaccination testing among students who received 3 doses of vaccine (N=2481) Interval (Years) Total N (%) Anti -HBs <10IU/L N (%) Anti -HBs ≥ 10 IU/L N (%) Odds Ratio Confidence Interval < 5 855 (34.5) 32 (3.7) 823 (96.3) Ref 5-10 931 (37.5) 81 (8.7) 850 (91.3) 2.45 1.6-3.7 11-15 634 (25.6) 57 (9.0) 577 (91.0) 2.54 ≥ 16 61 (2.5) 5 (8.2) 56 (91.8) 2.30 0.9-6.1 Irrespective of time since primary series to postvaccination testing, there were significantly more students with adequate anti-HBS levels. (((((Of note, percentage of students with anti-HBs less than 10 plateaus at approximately 8.5% , when tested 5 years of more from time of vaccination.)))))) Ref= reference group

Students with 3 primary vaccine doses Number of booster doses administered among students with anti-HBs <10 IU/L 1 booster dose (N=31) No booster dose (N=17) 3 booster doses (N=81) 2 booster doses ( N=46) Students with 3 primary vaccine doses (N=2481) Anti-HBs 10 IU/L (N=2306) Anti-HBs <10 IU/L (N=175) As per Midwestern University policy, students who failed to have anti-HBs levels greater than 10 following completion of the primary series were recommended to receive between 1 -3 booster (or additional) doses. ENTER Number of boosters given depended on the interpretation of anti-HBs level. 1 booster was given if levels were considered “just below cutoff”, 2 if “indeterminate”, And 3 if deemed “not immune” Of 175 such students, 17 did not receive a booster, 31 got a single booster, 46 received 2 booster doses and 81 received 3 booster doses

Response to booster dose(s) among students with anti-HBs <10 IU/L, by number of booster doses administered (N=175) Number of booster doses Number of students boosted Students with available test results Anti HBs <10 IU/L N (%) Anti HBs ≥ 10 IU/L N (%) 17 (0) 1 31 24 (100) 2 46 3 81 69 (2.9) 67 (97.1) 1-3 158 110 (1.8) (98.2) ENTER

Response to booster dose(s) among students with anti-HBs <10 IU/L, by number of booster doses administered (N=175) Number of booster doses Number of students boosted Students with available test results Anti HBs <10 IU/L N (%) Anti HBs ≥ 10 IU/L N (%) 17 (0) 1 31 24 (100) 2 46 3 81 69 (2.9) 67 (97.1) 1-3 158 110 (1.8) (98.2) All students who received 1 or 2 booster doses had documented antiHBs levels at or above 10.

Response to booster dose(s) among students with anti-HBs <10 IU/L, by number of booster doses administered (N=175) Number of booster doses Number of students boosted Students with available test results Anti HBs <10 IU/L N (%) Anti HBs ≥ 10 IU/L N (%) 17 (0) 1 31 24 (100) 2 46 3 81 69 (2.9) 67 (97.1) 1-3 158 110 (1.8) (98.2) Only ~3% of those who received 3 boosters had inadequate anti-hbs levels.

Response to booster dose(s) among students with anti-HBs <10 IU/L, by number of booster doses administered (N=175) Number of booster doses Number of students boosted Students with available test results Anti HBs <10 IU/L N (%) Anti HBs ≥ 10 IU/L N (%) 17 (0) 1 31 24 (100) 2 46 3 81 69 (2.9) 67 (97.1) 1-3 158 110 (1.8) (98.2) And among all students who received booster doses, 98% had an adequate antibody response.

Limitations Cannot exclude possibility of additional doses not documented in student health clinic record Time points for collection of anti-HBs levels after vaccination were variable Results may not be generalizable to other students or non-students of similar age Student health records are intended primarily for documenting compliance Our study also had several limitations: 1. Cannot exclude possibility of additional doses not documented in the student health clinic record 2. Time points for collection of anti-HBs levels after vaccination were variable 3. Results may not be generalizable to other students or non-students of similar age 4. Student health records are intended primarily for documenting compliance 1. Data available for analysis was limited to the vaccination record provided to the school by the student -Therefore we could not exclude the possibility of prior hepatitis B vaccinations or additional doses not documented in that record. 2. There was limited demographic and clinical data available for analysis For example: BMI listed was at matriculation and there was no smoking history In addition, the Student health records and database are intended primarily for documenting compliance as per the school’s interest or requirements 3. These results may not be generalizable to other healthcare students, or non students of similar age.

Conclusions 75% of students completed the 3-dose Hepatitis B vaccine series 94% of students who completed the 3-dose Hepatitis B vaccine series maintained anti-HBs levels ≥10 IU/L Most completed the primary series during adolescence (age ~ 15 yrs) IN CONCLUSION, 75% of students completed the 3-dose Hepatitis B vaccine series 94% of students who completed the 3-dose Hepatitis B vaccine series maintained anti-HBs levels ≥10 IU/L Most completed the primary series during adolescence (age ~ 15 yrs) “anamnestic response” can only be assesses with a PVT 2-4 weeks after the {{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{

Conclusions Shorter time interval between vaccination and postvaccination testing was associated with anti-HBs >10 IU/L Almost all (98%) students with available results had post-booster anti-HBs >10 IU/L after revaccination with 1-3 additional doses Shorter time interval between vaccination and postvaccination testing was associated with anti-HBs >10 IU/L Almost all (98%) students with available results had post-booster anti-HBs >10 IU/L after revaccination with 1-3 additional doses “anamnestic response” can only be assesses with a PVT 2-4 weeks after the {{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{

Acknowledgements Division of Viral Hepatitis Midwestern University Justina Groeger, MPH Joseph Towers, MD Jim Xing , PhD Catherine Fernandez Philip Spradling, MD Illinois Department or Public Health Craig Conover, MD Kenneth Soyemi, MD Elizabeth Barajas, MPH I’d like to that my collaborators at Midwestern University and the Illinois Department of Public Health, as well as my colleagues in the Division of Viral Hepatitis who assists with this study. THANK YOU!!! I’m happy to answer any questions National Center for HIV/AIDS, Viral Hepatitis, STD & TB Prevention Division of Viral Hepatitis

Additional Slides

Characteristics of Excluded Students (n=809) Total N (%) Median age (range) 27 (21-67) Gender Female 496 (61.3) Male 299 (36.0) Country of birth* US 266 (74.5) Other 91 (24.5) Characteristic Total N (%) Race/Ethnicity White, Non-Hispanic 498 (61.6) Black, Non-Hispanic 25 (3.1) Asian/PI 143 (17.7) Hispanic 18 (2.2) AI/ AN 1 (0.1) Other/Unknown 124 (15.3) Demographic characteristics among excluded students were similar for study participants Median age was 26 for study participants, and 27 for excluded students Both populations had similar distribution of gender (with predominance of females around 60%), White composed largest race/ethnic group folled by asians, blacks, hispanics and ai/an And most were born in the US

Characteristics of Chronic Carriers 2 reported born in US (both asian/pi); 4 born in foreign countries (Poland, China, Vietnam, Russia) Mean age at time of matriculation(range): 28.6 (23-40) 6/6 had documented lab or physician record supporting diagnosis *******What is recommendation for these students*****;

Study Population N= 3452 Abstracted Records N= 3140 Excluded due to: Irreconcilable records (2) Chronic HBV infection (6) Allergy to Vaccine (1) Missing DOB/ age at vaccination (235) N=2896 Missing Anti-HBs result N=2708 Limit to those who received 3 doses N=2693 Have titer result and appropriate vaccination dates N=2481

Characteristics of Students who received at least 1 dose of Vaccine and 1st Titer Characteristic (N=2896) Gender Male = 1057 (36.5%) Median age at start of primary series (range) 14.7 years (0-54.3 years) Race/Ethnicity White, Non-Hispanic 1811 (62.5%) Black, Non-Hispanic 36 (1.2%) Asian/Pacific Islander 485 (16.7%) Hispanic 55 (1.9%) American Indian/Alaska Native 3 (0.1%) Other/Unknown 506 (17.8%) Foreign-born* 316 (15.1%) BMI (mean ± std)** 23.5 ± 4.1 Hawaiian/Pacific Islander = 7 Add the vaccine dose # back *N= 2074 **N=2095

Age at Hepatitis B Primary Vaccine Series Among Students who received ≤ 3 doses (n=2708) Age in Years Anti HBs < 10 mIU/mL N (%) Anti HBs ≥ 10 mIU/mL N (%) χ2 p-value < 1 2 (25.0) 6 (75.0) .0007 1-5 7 (15.6) 38 (84.4) 6-10 48 (9.8) 442 (90.2) 11-20 113 (8.1) 1280 (91.9) 21-30 57 (8.4) 620 (91.6) 31-40 12 (16.0) 63 (84.0) ≥ 40 5 15

Median Ages and Time Intervals Study Population (n=2481) Median age of first dose in years (range) 14.5 (0-49.2) years Median age at completion of 3rd dose 15.5 (0.5-49.4) years Media time between 1st dose and anti-HBs 8.6 (0-24.3 mos) Median time between completion of series and titer(range) 2.2 (0-18) years Median interval between first booster and repeat anti-HBs * 7.9 (0.5-34) mos Mean time between completion of series and titer was 4.5 years * N= 158

Time interval from primary vaccine series to postvaccintion testing among students who received 3 doses of vaccine, MWU, 2004 – 2009 (n=2481) Interval (Years) Anti HBs <10 mIU/mL N (%) Anti HBs ≥ 10 mIU/mL N (%) χ2 p-value < 5 32 (3.7) 823 (96.3) <.0001 ≥ 5 143 (8.8) 1483 (91.2) Time interval from end of primary series to date of PVT testing was analyzed. Range of interval time is 0 to 24 years.

Characteristics of students with ≤ 3 doses & postvaccination serology (n=2643) Total N (range) Anti- HBs <10 IU/L N (range) Anti -HBs ≥10 IU/L OR CI Median age at start of primary series (years) 14.7 (0-49) 16.5(0-48.8) 15.7 (0-49) 0.10* Age groups at start of primary series in years N (%) Anti HBs < 10 mIU/mL N (%) Anti HBs ≥ 10 mIU/mL <1 8 (0.3) 2 (25.0) 6 (75) Ref 1-5 45 (1.7) 7 (15.6) 38 (84.4) 0.6 0.1-3.3 6-10 488 (18.5) 48 (9.8) 440 (90.2) 0.3 0.1-1.7 11-20 1378 (52.1) 109 (7.9) 1269 (92.1) 0.1-1.3 21-30 637 (24.1) 37 (5.8) 600 (94.2) 0.2 0.4-0.9 31-40 69 (2.6) (11.6) 61 (88.4) 0.4 0.1-2.3 ≥ 40 18 (0.7) 3 (16.7) 15 (83.3) 0.1-4.5 Median age at start of the primary series was ~ 15 years old. There was no association this variable and anti-HBs value Age was the categorized to further explore the association of antiHBs value across various age groups at start of primary series. - Only 8 students received vaccination during infancy and most received it between 11-30 years of age. - Regardless of age at which student started primary series, the majority maintained anti-HBs levels suggestive of immunity. - Vaccination at 21-30 years of age had protective effect on adequate antibody levels compared to those vaccinated at age than 1. }}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}} Age of MWU students in study(as measured by DOB to time of study) Mean age = 26.3 Median age = 26 Range= 16 - 60 Ref = reference group *t-test

Time interval from primary vaccine series to postvaccintion testing among students who received 3 doses of vaccine, MWU, 2004 – 2009 (n=2481) Interval (Years) Anti HBs <10 mIU/mL N (%) Anti HBs ≥ 10 mIU/mL N (%) χ2 p-value < 5 32 (3.7) 823 (96.3) <.0001 5-10 81 (8.7) 850 (91.3) 11-15 57 (9.0) 577 (91.0) ≥ 15 5 (8.2) 56 (91.8) Time interval from end of primary series to date of PVT testing was analyzed. This interval was categorized as shown here, but ranged from 0 to 24 years. 24% had PVT testing done 15 years or more after completing primary series. Irrespective of time since primary series to PVT, there were significantly more students with antiHBS levels greater than or equal to 10. Of note, percentage of students with anti-HBs less than 10 plateaus at approximately 8.5% , when tested 5 years of more from time of vaccination.

Midwestern University Hepatitis B Vaccination Policy Anti-HBs cutoff level are determined by lab at which test was done MWU will accept any prior anti-HBs levels done (no time limit) Booster recommendations: Anti-HBs Result # of boosters recommended Not immune 3 Indeterminate 2 Just below lower limit of immunity 1