Persistence of hepatitis B surface antibody and immune memory to hepatitis B vaccine among medical college students in Madinah

Comparison of Hepatitis B Surface Antibody Levels After Vaccination With Combined One Dose of Hexavalent Vaccine and Two Doses of Pentavalent Vaccine Versus Three Doses of Pentavalent Vaccine

BACKGROUND

Vaccination can effectively prevent hepatitis B virus (HBV) infection. Vaccination with 3 doses of hexavalent HBV-containing vaccines led to a higher Hepatitis B surface antibody (anti-HBs) antibody level than vaccination with 3 doses of pentavalent HBV-containing vaccines. Whether the substitution of one dose of hexavalent HBV-containing vaccine in the pentavalent regimen could lead to a higher anti-HBs antibody level remains unknown.

METHODS

A randomized, open-label controlled trial was conducted. Infants aged 30-120 days were randomly assigned to either a combined hexavalent/pentavalent regimen (hexavalent HBV-containing vaccine at 2 months of age and pentavalent HBV-containing vaccine at 4 and 6 months of age) or a 3-dose pentavalent regimen (pentavalent HBV-containing vaccine at 2, 4, and 6 months of age). Anti-HBs antibody levels were measured 3-6 months after the last vaccination.

RESULTS

Seventy-six infants were enrolled, 38 in each group. The geometric mean of anti-HBs antibody levels in the combined hexavalent/pentavalent group was significantly higher than that of the 3-dose pentavalent group [316.2 mIU/mL (95% CI: 173.8-575.4 mIU/mL) versus 81.3 mIU/mL (95% CI: 38.9-169.8 mIU/mL), P = 0.006]. By multivariate analysis, the combined hexavalent/pentavalent regimen (coefficient 0.57; P = 0.003) was associated with higher anti-HBs antibody levels, while body weight <10th percentile (coefficient -0.85; P = 0.006) and receiving concomitant pneumococcal conjugated vaccines (coefficient -0.65; P = 0.001) were associated with lower anti-HBs antibody levels.

CONCLUSION

Substituting the first dose with a hexavalent HBV-containing vaccine in the pentavalent regimen for HBV vaccination led to higher anti-HBs antibody levels in infants. Concomitant pneumococcal conjugated vaccine administration may have an adverse impact on anti-HBs antibody level.

Impaired humoral immune response to hepatitis B vaccine in patients on maintenance hemodialysis

Hepatitis B virus (HBV) infection is a worldwide health problem. We aimed in this study to investigate the humoral immune response derived to HBV vaccine following completing the vaccine series in Madinah. Two hundred and two Saudi hemodialysis (HD) patients were included in this cross-sectional study. Mean concentration of Hepatitis B surface antibody (anti-HBs) was significantly higher among patients who received the vaccination twice compared to patients who received the vaccination only after starting hemodialysis (252 ± 489 mIU/mL vs. 144 ± 327 mIU/mL, respectively, p = 0.008). Almost half of the study sample were non-protected and showed anti-HBs concentration < 10 mlU/mL. In contrast, 20.3% (n = 41) were identified as poor responders (10-100 mlU/mL) and only 28.2% (n = 57) were identified as good responders (10-100 mlU/mL). However, the latter two groups were accounted as protected (48.5%, n = 98). Patients sex was associated with anti-HBs concentration (non-responders; poor responders; good responders), where significantly higher proportion of good responders were females compared to males (p = 0.007). In conclusion, HBV vaccine is efficient to elicit humoral immune response in hemodialysis patients.

Investigation the longevity of hepatitis B surface antibody in vaccinated students of Hormozgan university of medical sciences

Background and Objectives

Hepatitis B is a common chronic viral infection in humans. Universal use of hepatitis B vaccine is crucial for controlling the infection, but the duration of vaccine-induced immunity remains uncertain. This study aimed to assess hepatitis B antibody levels (anti-HBs) after vaccination in infancy and adolescence, and explore the relationship between immunity levels and variables such as age, sex, BMI, place of birth, and duration since last vaccination among students at Hormozgan University of Medical Sciences from 2019 to 2021.

Materials and Methods

The study included 1134 students who completed a questionnaire and provided blood samples for ELISA-based measurement of antibody titers.

Results

The findings revealed that 727 students (64.1%) had no protective antibody level (anti-HBs <10 mIU/ml), 299 (26.4%) had partial immunity (anti-HBs 10-100 mIU/ml), and 108 (9.5%) had complete immunity (anti-HBs >100 mIU/ml). No statistically significant relationships were observed between anti-HBs titer and age, sex, or BMI. However, antibody titer decreased with increasing time since last vaccination (P<0.001).

Conclusion

This study highlights the decline in antibody titer over time following primary vaccination. Sustained immunity against hepatitis B virus relies on antibody durability or robust immunological memory, suggesting the importance of timing booster vaccinations.

Hepatitis B virus immunity prior to and after administration of a ‘booster’ dose of vaccine among health-care students at a South African university

Background

Health-care students (HCSs) are at risk of occupational exposure to hepatitis B virus (HBV) infection despite an effective hepatitis B vaccine (HepB) being available. The majority of current HCSs are born after HepB was introduced into the South African Expanded Programme on Immunisation in 1995. Thus, it is assumed that having received HepB in infancy, a single 'booster' dose would suffice. This study aimed to investigate HBV immunity prior to and after administration of a HepB 'booster' dose.

Methods

Hepatitis B surface antibody (anti-HBs) levels were determined in first year HCSs at the University of the Witwatersrand, before and after receiving the 'booster'. Participant demographics and HepB history were captured using a structured questionnaire.

Results

Before receiving the 'booster', 56% (101/180) had anti-HBs < 10 mIU/mL and were non-immune. A further 35% had anti-HBs levels of 10 - 99 mIU/mL, and 9% had ≥100 mIU/mL. <30% of HCSs self-reported completion of a three-dose primary series, which was significantly associated with higher baseline anti-HBs levels compared to those with a partial schedule (p = 0.045). Following vaccination, 39% (71/180) returned for follow-up with a significant median (IQR) increase of 476 (151 - 966) mIU/mL (p < 0.001). Of the 45 students who had non-immune baseline levels, 73% (33/45) responded with ≥100 mIU/mL, 16% (7/45) with 10 - 99 mIU/mL and 11% (5/45) remained non-immune. Levels of ≥100 mIU/mL were achieved by 100% of students with baseline levels ≥10 mIU/mL (n = 26).

Conclusion

More than half of the HCSs were not immune to HBV prior to receiving the recommended 'booster' vaccine. Following vaccination, 7% (5/71) remained unprotected. This study highlights that in the absence of vaccination records and without confirming the immune status of HCSs, it cannot be assumed that HCSs will be protected following a 'booster'. Policy reform and inclusion of serological tests for immunity prior to HCSs initiating clinical exposure are recommended.

Epidemiology of Chronic Hepatitis B Infection in the Cohort of College Students with Vaccination in Taiwan

After the mass vaccination project in Taiwan, the prevalence of the hepatitis B virus (HBV) infection for the college-aged population of 18 to 21 years is uncertain. We aimed to investigate the prevalence of hepatitis B markers in different birth cohorts. A total of 38,075 students in universities in Kaohsiung area undergoing entrance examinations between July 2006 to September 2020 were included. Seroprevalence of the hepatitis B surface antigen (HBsAg) and hepatitis B surface antibody (anti-HBs) status and laboratory data were collected. The seropositive rate of HBsAg was less than 1% for students born after 1991. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST), were significantly higher, and body mass index (BMI) was significantly lower in HBV carriers compared to those who were not carriers (all p < 0.001). Multivariate logistic regression showed that age, male, higher BMI, and positive HBsAg were risk factors of abnormal ALT value. A decrease in the positive rate of anti-HBs which was significantly higher in the cohort of plasma-derived vaccines than recombinant vaccines was found. We concluded that there were decreasing trends in seropositive rates of HBsAg and anti-HBs for students of the college-aged population in the Kaohsiung area. The status of HBsAg was a predictive factor of abnormal ALT levels. The period effect on anti-HBs seropositivity for DNA recombinant vaccine somehow existed.

Long-Term Effectiveness of Hepatitis B Vaccination in the Protection of Healthcare Students in Highly Developed Countries: A Systematic Review and Meta-Analysis

Hepatitis B virus represents an important global health problem. In highly developed countries, mass vaccination campaigns of newborns in recent decades have drastically reduced the proportion of carriers. However, workers exposed to blood and body fluids, including healthcare students, can be at risk of exposure. In order to assess the proportion of susceptible individuals in the specific population of healthcare students in highly developed countries, a systematic review and meta-analysis was performed to summarize the evidence on the persistence of humoral immune protection induced by the primary cycle of hepatitis B vaccination, as well as the proportion of true non-responders. Forty-six studies were included in the final analysis (52,749 participants). Overall, the seroprotection prevalence at the pre-exposure assessment was equal to 73.8% (95% CI 69.1-78.0); the prevalence of anamnestic response following the administration of a challenge dose was 90.9% (95% CI 87.7-93.3), demonstrating a high proportion of persistence of vaccination-induced immunity. Among those without evidence of anamnestic response, 5.0% (95% CI 2.1-11.5) were non-responders following the completion of a secondary immunization cycle. These findings demonstrate that the majority of healthcare students vaccinated with the complete HBV primary cycle maintain an effective humoral immunity against this pathogen for over two decades.

A, Osman A. E, Abdullah J. A, Ahmad M. S, Mohammed H. N, Nahid K. E, Mohammed A. A, Saeed M. A, Mutaib M. M. Persistence of hepatitis B surface antibody to hepatitis B vaccine among medical college students in Najran University, Saudi Arabia

Around 257 to 291 million people worldwide are infected with the hepatitis B virus (HBV). Immunization is one of the most effective ways to combat HBV infection. Saudi Arabia implemented a mandatory hepatitis B immunization program in 1989. This project investigated the levels of hepatitis B surface antibodies (anti-HBs) among medical students in the college of applied medical science at Najran University in December 2020. Students (n=82) were tested for anti-HBs levels using a chemiluminescent microparticle immunoassay (CMIA). Anti-HBs levels were the main outcome measures. Results showed that about 81.7% of participants had an insufficient amount of Anti-HBs levels (<10 IU/ L) compared to 18.3 % of participants who had protective levels of anti-HBs (≥10 IU/ L). However, 78.5% of the reactive group was at risk of losing immunity with a level between 12 and 42 IU/ L. Our study also showed an association between the age and the level of anti-HBs. Moreover, male students were at more risk than female students. Our results showed a strong relationship between Blood Groups and Anti-HBs antibody levels. The O+ (with 38.8%) and A+ (with 25.4%) blood groups showed the highest percentage amongst participants who had inadequate protection of anti-HBs (<10 IU/ L). Thus, data helps in our understanding and observations on anti-HBV immunity in individuals twenty years after being vaccinated as a child. According to the findings of our study, a large majority of students had a non-protective anti-HBs titer.

Seroprotection of Hepatitis B Vaccine in Dental Students Two Decades after Infant Immunization and the Possible Need for Revaccination

OBJECTIVES

 This study aimed to assess hepatitis B surface antibody (anti-HBs) persistence among dental students two decades after infant vaccination and immune response after revaccination or booster dose in nonimmune groups.

MATERIALS AND METHODS

 A cross-sectional study was performed using laboratory reports for anti-HBs performed to dental students at the Umm al-Qura University from 2016 to 2020. Reports were classified according to baseline antibody titer into group I (titer <10 mIU/mL), group II (titer 10 to <100 mIU/mL), and group III (titer ≥100 mIU/mL). The basal antibody titer of each group was correlated to student's gender and birth year and compared with postrevaccination or booster dose titer in groups I and II.

STATISTICAL ANALYSIS

 Data of baseline and postrevaccination anti-HBs antibody titers were analyzed using Statistical Package for Social Science (SPSS). One-way ANOVA was used to compare between different means for antibody titers of students as well as baseline and postrevaccination antibody levels for nonimmune students with nonprotective antibody titers. Pairwise multiple comparison of the difference between baseline and postrevaccination anti-HBs antibody titers were done by post hoc Tukey's honestly significant difference (HSD) test. Chi-squared test was used for comparing between the frequencies. A p-Value of ≤0.05 was considered significant and p < 0.01 was considered highly significant.

RESULTS

 A significant percentage (73.6%) of students had antibody titer <10 mIU/mL, while only 4.8% had antibody titer ≥100 mIU/mL with nonsignificant difference between both genders (χ ² =3.784, p = 0.151). A statistically nonsignificant difference was also found between the three categories of anti-HBs antibody titers among students with different birth dates (χ ² = 13.817, p = 0.182). After revaccination of nonimmune students, 100% of them showed strongly protective antibody titers with mean of 842.88 to 844.58 mIU/mL. A highly significant difference was observed between the mean baseline and postrevaccination antibody titers in both genders, with a higher mean of post revaccination (p = 0.000).

CONCLUSION

 Two decades after infant immunization, a significant percentage of dental students failed to maintain the anti-HBs seroprotective titer. So titer measurement should be made compulsory before they begin their clinical training and revaccination or booster dose should be given to nonimmune students to maintain a high protection level.

Association of viral load with age, gender, disease severity and death in SARS-CoV-2 variants

In the current study, the relationship between viral load, demographic characteristics, and disease information in 1007(48.5%) patients with Delta variant (B.1.617.2), and 1070 (51.5%) patients with Alpha variant (B1.1.7) mutations was investigated. We found that there was a significant difference in viral load between patients who died from the Alpha variant and those who were discharged (p<0.05). Nevertheless, no significant difference was observed in patients with Delta variant. The viral load in patients who died from the Alpha variant was significantly higher than those who were discharged (p<0.05). The viral load was found to be higher in females in patients with Delta variant, whereas it was very close in males and females in patients with Alpha variant (p>0.05). No significant difference was detected between the cycle threshold values (Ct) and disease severity. In terms of the mean Ct values, statistical differences were observed in patients with Delta and Alpha variant. The Alpha variant was found to have a higher viral load than the Delta variant. Furthermore, Delta variant was found to be higher in the 40-year-old and under-age group than in the Alpha variant, whereas the Alpha variant was higher in the 40-year-old and older group. While the rate of moderate and severe patients in Alpha variant was found to be higher, the rate of mild survivors was found to be higher in Delta variant. In conclusion, The increase in vaccination prior to the appearance of the Delta variant in our region may have influenced the viral load and clinical status of the patients. This article is protected by copyright. All rights reserved.

The seroprevalence of the hepatitis B virus in Italian medical students after 3 decades since the introduction of universal vaccination

OBJECTIVES

Since 1991 hepatitis B vaccination has been mandatory for all newborns in Italy. The aim of the study was to verify the long-term seroprevalence and the efficacy of hepatitis B vaccination in medical students of the University of Siena.

MATERIAL AND METHODS

A cross-sectional observational study was conducted on a population of 850 medical students of the University of Siena (322 males and 528 females, mean age: 23 years) by obtaining from the medical reports the serological analysis data for the total anti-hepatitis B antibodies (HBsAb) and information on hepatitis B vaccination (number of vaccine doses, age at the first vaccination, time since the final vaccination dose, country of origin). Raw odds ratios (ORs) and 95% confidence intervals (CIs) were initially calculated to evaluate the association between 2 variables. The adjusted ORs were then calculated using a multivariate logistic regression model to study the association between the variables and the possible confounding factors.

RESULTS

Overall, 593 students (69.76%) were immunized against hepatitis B, while 257 (30.24%) had HBsAb antibody titer <10 mIU/ml. From the OR calculation, an inverse correlation emerged between seropositivity to hepatitis B and age, and between seropositivity to hepatitis B and the age at the first vaccination dose. There was also a correlation between seropositivity and the number of vaccination doses received. By performing the multivariate logistic analysis, correlations with these variables were confirmed.

CONCLUSIONS

A significant part of the studied population was not immunized against hepatitis B virus, despite the fact that vaccination had been carried out as prescribed by law. The results of the study reaffirm the importance of health surveillance in subjects at biological risk such as medical students. Int J Occup Med Environ Health. 2022;35(1):75-80.

Human Cytomegalovirus Seroprevalence Among Blood Donors in the Madinah Region, Saudi Arabia

Background and objective

Human cytomegalovirus (HCMV), a double-stranded DNA virus of the Herpesviridae family, can remain latent for long periods of time. HCMV may cause severe illness in immunocompromised patients and is associated with congenital anomalies. This study aimed to determine the anti-HCMV immunoglobulin G (IgG) and IgM antibody seroprevalence among blood-donating Saudi men in the Madinah region.

Methods

A total of 375 blood-donating Saudi men were recruited from the Central Blood Bank in Madinah, the Kingdom of Saudi Arabia (KSA), and stratified into three age groups: 18-30, 31-40, and 41-61 years. Anti-HCMV IgG and IgM antibody levels were measured by enzyme-linked immunosorbent assay (ELISA). Pearson’s correlation coefficient was used to correlate antibody levels with variables.

Results

Most of the tested samples (95.73%, n=356) were positive for anti-HCMV IgG antibodies, but only 1.6% (n=6) were positive for both IgM and IgG antibodies, and all of them belonged to the age groups of 31-40 and 41-61 years. A strong inverse correlation was found between anti-HCMV IgG antibody levels and age (r=−0.51, p<0.0001). Additionally, there was an inverse correlation between anti-HCMV IgG antibody levels and body mass index (BMI) (r=−0.11, p=0.036). No correlations were found between anti-HCMV IgG levels and hemoglobin levels or blood groups of the participants.

Conclusions

Blood-donating Saudi men in Madinah had a high seroprevalence of anti-HCMV IgG antibodies, indicating previous viral exposure. Age and BMI might influence the humoral immunologic memory response against HCMV, which appears to be endemic in Madinah.

Long-term Immunity Against Hepatitis B Virus After Routine Immunization Among Adults Visiting Primary Care Centers in Riyadh, Saudi Arabia

Objective This study aimed to determine the persistence of induced immunity against hepatitis B virus (HBV) among adults routinely vaccinated during their infancy and correlate the level of induced immunity with participant characteristics. Methodology This was a cross-sectional study conducted among visitors to primary care centers of the Ministry of Health (MOH) in Riyadh, the Kingdom of Saudi Arabia (KSA) during the period from August 2020 to January 2021. The study population included healthy adults of both genders who had received full doses of the HBV vaccine in infancy. Data related to participant characteristics were collected using a self-administered questionnaire. A blood sample was then taken from each participant to measure the serum level of hepatitis B surface antigen (HBsAg), antibodies against HBsAg (anti-HBs), and antibodies against hepatitis B core antigen (ani-HBc). Results A total of 400 subjects participated in the study; the mean age of the cohort was 25 years. Almost all of them were Saudis (99.30%), and more than half (57.50%) were males. Only 24.30% had an anti-HBs antibodies level of ≥10 IU/L, and all respondents were negative for HBs antigen. No significant association between participant characteristics and anti-HBs antibody levels was found. Conclusion A decline in immunity many years after HBV vaccinations taken in infancy has been well-documented. However, for low-risk populations, the boosting of HBV vaccines is probably unnecessary since the immune memory provides sufficient protection despite low or undetectable anti-HBs antibodies.

Assessment of SARS-CoV-2 Anti-Spike IgG Antibody in Women and Children in Madinah, Saudi Arabia: A Single-Center Study

BACKGROUND

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Information on the prevalence of SARS-CoV-2 antibodies in women and children in Madinah has been limited. The current study aimed to evaluate SARS-CoV-2 IgG seropositivity among women and children at Madinah Maternity and Children's Hospital.

METHODS

In this cross-sectional study, 579 participants were recruited between January and April 2021 from Madinah Maternity and Children's Hospital, Saudi Arabia. Data concerning age, sex (for children), blood group, and height and weight (for women) were collected from the hospital database. SARS-CoV-2 anti-spike (anti-S) IgG antibodies were detected by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Over 58% of children (n = 195), including 60% of children ≤ 1 year (n = 75), and 50.2% (n = 124) of women were SARS-CoV-2 anti-S IgG seropositive. Significantly higher anti-S IgG levels were observed in children than in women (0.78 ± 1.05 vs. 0.65 ± 0.98, p = 0.008). Compared with women, children had higher odds of high SARS-CoV-2 anti-S IgG levels (odds ratio: 1.41; 95% confidence interval: 1.01-1.97; p = 0.041). No significant associations were observed for anti-S IgG levels with age in women or children or with body mass index among women.

CONCLUSION

Non-reported COVID-19 infections were more prevalent among children than women, and non-reported COVID-19 infections children represent a viral transmission risk; therefore, increased screening, especially among school-aged children, may represent an important COVID-19 preventive control measure.

Hepatitis B-C and human immunodeficiency virus: seroprevalence and associated factors among health students in Saudi Arabia

OBJECTIVES

To assess the seroprevalence of Hepatitis B (HBV), Hepatitis C (HCV), and Human Immunodeficiency Virus (HIV) among newly admitted health track students in a large university in the Eastern Province of Saudi Arabia, and determine the students' immunity against HBV, and bloodborne viral infection risk factors or practices among them.

METHODS

Information about the 1145 students, vaccination history, and exposure to bloodborne viral infections risk factors/practices were collected using a structured questionnaire during August 2020. The results of serological data were obtained from students' electronic files.

RESULTS

All students tested negative for HBV, HCV, and HIV infections. The seroprevalence of positivity against HBV was 25.8%, and the frequencies of students with protective levels of anti-HBV were inversely related to their age. The majority (70.8%) of students had 1 or 2 identifiable risk factors for bloodborne diseases, and the most frequent risk factor was history of dental intervention. Female students were more than four-times likely to be in the high-risk group for bloodborne infections than males (OR = 4.4; 95% CI: 3.3-5.9). Being from the Central Province of Saudi Arabia (OR = 1.9; 95% CI: 1.2-3.1) and having a mother's educational level of master or doctorate (OR = 3.0; 95% CI: 1.3-6.7) were found to be independent predictors of being in the high-risk group. On the other hand, having a family member in the healthcare field was found as a predictor of being in the low-risk group for bloodborne diseases (OR = 0.7; 95% CI: 0.5-0.9).

CONCLUSION

About three-fourth of students in this study were susceptible to HBV. Our findings stress the need to develop policies to raise awareness regarding bloodborne infectious diseases, in addition to expanding access to HBV vaccination for healthcare staff, especially in older ages.

Association of Viral Load in SARS-CoV-2 Patients With Age and Gender

Background: The coronavirus disease 2019 (COVID-19), caused by the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), is a global public health emergency. Age and sex are two important factors associated with risks and outcomes of various diseases. COVID-19 morbidity also seems to be affected by patient age and sex. It has been found that older age groups have more severe COVID-19 symptoms and higher fatality rates while children tend to have lower prevalence and milder symptoms than adults.

Methods: The study reviewed electronic medical records of COVID-19 patients from Madinah city, Saudi Arabia. The study included all cases who tested positive (n = 3,006) between March 20 and May 22, 2020. Data were obtained from the Health Electronic Surveillance Network (HESN) database.

Results: Approximately 80% of the study sample were males and half were in the 30–40-year-old age group. The Ct value of the whole sample ranged from 15.08 to 35, with a mean of 27.44 (SD: 5.23; 95% C.I. = 27.25–27.66). The means of Ct values varied between age groups from 27.05 to 27.82. Analysis of the mean differences between age groups using one-way ANOVA indicated no statistically significant difference among the groups (F_6,2999 = 1.63; p-value = 0.135). A comparison of mean Ct values of males (n = 2,422) and females (n = 584) revealed that males had a statistically significant higher mean Ct value (27.61 ± 5.20) than females (26.72 ± 5.31). The difference between the means of the two groups was −0.89 (95% C.I. = −1.36 to −0.42; t-test −3.71; df = 3,004; p-value < 0.001).

Conclusion: The study found no statistically significant difference in viral loads between age groups. It showed that females had a higher SARS-CoV-2 viral load compared to males. The findings have implications for preventive strategies. Further studies are needed to correlate viral load with clinical symptoms and outcomes.

Kinetics of Anti-Hepatitis B Surface Antigen Titers in Nurse Students after a Two-Year Follow-Up

Infection caused by hepatitis B virus (HBV) can be prevented through a safe and effective vaccine. This study analysed the kinetics of serum antibodies against hepatitis B surface antigen (HBsAg) (anti-HBs) titers in relation to previous vaccine boosters in Italian nursing students who were followed up for two years. Serum anti-HBs titers were evaluated at the first visit, after vaccine booster (if required) and at visit after two years. Overall, 483 students (mean age = 21.7 years; SD = 3.7) with median anti-HBs IgG titer of 6 mUI/mL (interquartile range (IQR) = 0-34) were enrolled. A total of 254 (52.5%) students with a titer lower than 10 mIU/mL were offered an anti-HBV booster at the first visit. Among these students, an exponential relation between anti-HBs IgG titer, one month after HBV booster and anti-HBs IgG titer two years later was found (y = 3.32 exp (0.0045x); R2 = 0.48; p < 0.001). Students with anti-HBV titer higher than 10 mIU/mL (N = 229) were followed up, and anti-HBs IgG titers at follow-up visit linearly correlated with anti-HBV baseline titers (y = 0.86x + 26.2; R2 = 0.67; p < 0.001). A decrease in anti-HBs titers can be expected a few years after the anti-HBV booster dose. This reduction is more pronounced than that observed in students not administered the booster dose and is exponential with respect to basal titers assessed after the booster dose.