Seroprotection following hepatitis B vaccination in health care workers at a dental teaching hospital in south India: an observational study

Abstract

Objective  To evaluate the serological response to hepatitis B vaccination among health care workers (HCWs) in a dental teaching institution in South India and to assess factors influencing seroprotection.

Methods  This observational cohort study included 217 HCWs from a dental teaching hospital. Participants received the recombinant hepatitis B vaccine according to the standard three-dose schedule (0, 1, and 6 months). Anti-hepatitis B surface antibody (anti-HBs) titers were measured two months after completion of vaccination using enzyme-linked immunosorbent assay. Seroprotection was defined as anti-HBs ≥10 mIU/mL. Associations between seroprotection and demographic variables, including age, gender, ethnicity, and number of vaccine doses, were analyzed using chi-square and independent t-tests.

Results  Among the participants, 203 (93.5%) completed the three-dose vaccination schedule. The overall seroprotection rate was 89.2% in the three-dose group and 85.7% in the two-dose group, with no statistically significant difference (p=0.691). Younger participants (≤30 years) demonstrated significantly higher seroprotection rates (p=0.034) and higher mean anti-HBs titers (p=0.049). No significant differences were observed between males and females (p=0.501). Seroprotection varied significantly across ethnic groups, with Malaysian participants showing the highest response rates (p=0.05).

Conclusion  Although hepatitis B vaccination provides substantial protection among HCWs, a proportion of individuals remain non-seroprotected despite completing the recommended vaccination schedule. Age and ethnicity significantly influence vaccine response. These findings highlight the importance of post-vaccination antibody monitoring and the need for targeted revaccination strategies in high-risk populations.

Keywords:
Hepatitis B; Vaccination; Health personnel; Antibodies; Occupational exposure

Introduction

Hepatitis B virus (HBV) infection and its complications remain a major global public health concern, with more than 240 million chronic carriers and an estimated 500,000–1.2 million deaths annually due to chronic hepatitis, cirrhosis, and hepatocellular carcinoma¹. Health care workers (HCWs) are at particularly high risk, being approximately four times more likely than the general population to acquire HBV infection. Most infections in HCWs result from occupational exposure to infected blood or body fluids through sharps injuries, such as needle-stick injuries, or from contaminated medical instruments, with an estimated 66,000 cases and 261 deaths annually in developing countries². In India, earlier studies have reported HBV prevalence among HCWs of 10% in 1992³, 2.21% in 1998⁴, and 3.7% in 2017⁵.

The risk of transmission following a needlestick injury is approximately 0.2–0.5% for human immunodeficiency virus (HIV), 3–10% for hepatitis C virus (HCV), and as high as 40% for HBV⁶. Unlike other blood-borne pathogens, HBV is preventable by vaccination and is more infectious than HIV, with the ability to survive in dried blood for at least one week⁷. Studies have shown that physicians and dentists, particularly those involved in surgical and invasive procedures, are at significantly higher risk of HBV exposure compared to other health care professionals⁷.

Vaccination is the most effective prophylactic measure against occupational HBV infection. The World Health Organization (WHO) reports that the recommended three-dose vaccination schedule provides approximately 95% seroprotection⁸. Nevertheless, vaccine response varies among individuals, and non-response or inadequate response has been increasingly reported⁹,¹⁰. Non-responders remain at risk of acquiring HBV infection, with the potential for progression to serious sequelae¹¹.

Several factors, including ethnicity, genetic polymorphisms, immunosuppression, vaccine storage conditions, obesity, diabetes, and gender, have been implicated in influencing vaccine response¹². In particular, human leukocyte antigen (HLA) polymorphisms play a critical role in modulating the immune response¹³. Studies indicate that 10–15% of individuals may not respond adequately to the standard three-dose vaccination regimen¹³-¹⁶. Given these observations, assessment of post-vaccination anti-HBs titers is essential for monitoring protective immunity among HCWs.

In recognition of these risks, the Dental Council of India has mandated HBV vaccination or proof of immunity for all dental students prior to clinical exposure. However, infection control incidents are often underreported, and vaccination records are not always systematically maintained. Furthermore, there is a paucity of data evaluating vaccine response among HCWs in our institution. Therefore, the present study aimed to determine the prevalence of responders and non-responders to HBV vaccination among HCWs in a dental teaching hospital in Mangalore, South India.

Material and Methods

Study Design and Participants

This observational cohort study was conducted among health care workers (HCWs), including faculty members, students (preclinical II Bachelor of Dental Surgery students prior to clinical training), and non-teaching staff at a dental teaching institution in Mangalore, South India. The study was carried out as part of an institutional hepatitis B vaccination program conducted between 2012 and 2013. Written informed consent was obtained from all participants prior to enrollment.

Participants aged between 19 and 55 years were included in the study. Individuals with a history of jaundice, family history of hepatitis, prior exposure to infected sharps (including tattoos), blood transfusion, or previous hepatitis B vaccination were excluded. A detailed medical history, including smoking status, alcohol consumption, diabetes, allergies, drug intake, and immunosuppressive conditions, was recorded at baseline.

Sample Size

The sample size was calculated based on an expected 5–10% prevalence of non-response to the standard three-dose hepatitis B vaccination regimen, as reported in previous studies¹³.

Vaccination Protocol

All participants received 1 mL of a recombinant second-generation hepatitis B vaccine (Gene Vac-B, Serum Institute of India) containing 20 µg of purified hepatitis B surface antigen. The vaccine was administered intramuscularly in the deltoid region following the Centers for Disease Control and Prevention (CDC) recommended three-dose schedule (0, 1, and 6 months).

Assessment of Anti-HBs Levels

Anti-hepatitis B surface antibody (anti-HBs) titers were measured two months after completion of the vaccination schedule using an enzyme-linked immunosorbent assay (ELISA). Seroprotection was defined as an anti-HBs level ≥10 mIU/mL. Participants with anti-HBs levels <10 mIU/mL were classified as non-responders.

Statistical Analysis

Statistical analysis was performed to evaluate the association between seroprotection and demographic variables, including age, gender, ethnicity, and vaccination status. The chi-square test was used to assess associations between categorical variables. Mean anti-HBs titers were compared between groups using the independent Student’s t-test. A p-value ≤0.05 was considered statistically significant. All analyses were performed using IBM SPSS Statistics for Windows, Version 20.0 (IBM Corp., Armonk, NY, USA).

Ethical Considerations

The study was conducted in accordance with the Declaration of Helsinki. Ethical approval was obtained from the Institutional Ethics Committee of Manipal College of Dental Sciences, Manipal Academy of Higher Education ( IEC Approval No: 14111). Written informed consent was obtained from all participants prior to inclusion in the study.

Results

A total of 217 participants were included in the study, comprising 49 males (22.6%) and 168 females (77.4%), with a female-to-male ratio of 3.4:1. The majority of participants were aged ≤30 years (163, 75.1%), followed by 31–40 years (24, 11.1%), 41–50 years (26, 12.0%), and >50 years (4, 1.8%). Students constituted 69.1% (n=150) of the study population, while non-teaching staff and faculty accounted for 16.1% (n=35) and 14.7% (n=32), respectively. Based on ethnicity, 102 participants (47.0%) were North Indians, 88 (40.6%) were South Indians, and 27 (12.4%) were Malaysians (Table 1).

Table 1
Demographic characteristics and vaccination status of participants in relation to seroprotection

Variable	Non responders		Seroprotected		Total	Chi square	P value
		N %		N %
GENDER
F	19	(79.20)	149	(77.20)	168	0.047	0.828
M	5	(20.80)	44	(22.80)	49
AGE
<=30 YEARS	14	(58.30)	149	(77.20)	163	4.066	0.044*
31-40	5	(20.80)	19	(9.80)	24
41-50	3	(12.50)	23	(11.90)	26
>50 YEARS	2	(8.30)	2	(1.00)	4
ETHNICITY
NORTH INDIAN	8	(33.30)	94	(56.60)	102	4.576	0.032*
SOUTH INDIAN	16	(66.70)	72	(43.40)	88
GEOGRAPHY
INDIAN	24	(100)	166	(86.00)	190	3.835	0.05*
MALAYSIAN	0	(0.00)	27	(14.00)	27
DOSES
TWO DOSES	2	(8.30)	12	(6.20)	14	0.158	0.691
THREE DOSES	22	(91.70)	181	(93.80)	203

• P<0.05 significant

Vaccination Status

Of the total participants, 203 (93.5%) completed the three-dose vaccination schedule, whereas 14 (6.5%) received only two doses. All partially vaccinated individuals were students (Table 1).

Seroprotection Rates

Of the total participants, 203 (93.5%) completed the three-dose vaccination schedule, whereas 14 (6.5%) received only two doses. All partially vaccinated individuals were students (Table 1).

Age and Gender

Seroprotection rates were significantly higher among participants aged ≤30 years (91.9%) compared to those aged 31–40 years (79.2%), 41–50 years (88.5%), and >50 years (50%) (p=0.034). In addition, younger participants demonstrated significantly higher mean anti-HBs titers compared to older participants (p=0.049).

No statistically significant difference in seroprotection was observed between females (89.1%) and males (89.4%) (p=0.501). However, males exhibited significantly higher mean anti-HBs titers than females (p=0.05) (Tables 2 and 4).

Table 2
Association of age, gender, and ethnicity with anti-HBs titers among fully vaccinated participants (three-dose regimen).

	Anti-HBS titres OF 203 three dose participants						TOTAL	Chi square	p-value
	<10		10-100		>100
	N %		N %		N %
AGE
<=30 YEARS	12	(8.10)	12	(8.10)	125	(83.90)	149	11.046	0.087
31-40	5	(20.80)	3	(12.50)	16	(66.70)	24
41-50	3	(11.50)	2	(7.70)	21	(80.80)	26
>50 YEARS	2	(50.00)	0	(0.00)	2	(50.00)	4
GENDER
F	17	(10.90)	15	(9.60)	124	(79.50)	156	1.383	0.501*
M	5	(10.60)	2	(4.30)	40	(85.10)	47
ETHNICITY
NORTH INDIAN	6	(6.20)	9	(9.40)	81	(84.40)	96	14.42	0.006*
SOUTH INDIAN	16	(19.30)	8	(9.60)	59	(71.10)	83
MALAYSIAN	0	(0.00)	0	(0.00)	24	(100.00)	24

• *P<0.05 is significant

Table 3
Seroprotection rates according to demographic characteristics in the three-dose regimen group.

	NON-RESPONDERS	SEROPROTECTED	Total	Chi square	p-value
	N %	Count
GENDER
F	17 (77.30)	139 (76.80)	156	0.003	0.96
M	5(22.70)	42(23.20)	47
AGE
<=30 YEARS	12(54.50)	137 (75.70)	149	4.492	0.034*
31-40	5(22.70)	19(10.50)	24
41-50	3(13.60)	23(12.70)	26
>50 YEARS	2(9.10)	2(1.10)	4
GEOGRAPHY
NORTH INDIAN	6(27.30)	90 (49.70)	96	3.308	0.069
SOUTH INDIAN	16 (72.70)	67 (37.00)	83
MALAYSIAN	0 (0.00)	24(13.30)	24
ETHNICITY
NORTH INDIAN	6 (27.30)	90 (57.30)	96	7.008	0.008*
SOUTH INDIAN	16 (72.70)	67(42.70)	83

• *P<0.05 is significant

Table 4
Mean anti-HBs titers by gender, age, and ethnicity among health care workers completing the three-dose regimen

Variable		N	Mean	Std. Deviation	Std. Error Mean	95% confidence interval		t	df	p-value
						Lower limit	Upper limit
GENDER	M	47	829.1758	418.8875	61.10103	768.0748	890.2769	1.988	78.54	0.05
	F	156	689.2066	436.5862	34.95487	654.2517	724.1614
AGE	<30	149	762.2021	400.6306	32.82094	729.3812	795.023	1.996	78.224	0.049
	>=30	54	609.6181	507.4117	69.04998	540.5681	678.6681
ETHNICITY	NORTH INDIAN	96	757.0576	405.5299	41.38922	715.6684	798.4468	2.148	159.599	0.033
	SOUTH INDIAN	83	611.3151	489.8536	53.76841	557.5467	665.0835
GEOGRAPHY	INDIAN	179	689.4787	451.2475	33.72782	655.7509	723.2065	-5.974	95.074	<0.001
	MALAYSIAN	24	961.2836	149.5891	30.53474	930.7489	991.8184

• *P<0.05 significant

Ethnic Background

All Malaysian participants (100%) achieved seroprotection, compared with 93.8% of North Indians and 80.7% of South Indians. Differences in seroprotection between ethnic groups were statistically significant (p=0.05).

Furthermore, mean anti-HBs titers were significantly higher among Malaysian participants compared to Indian participants (p<0.001), and among North Indians compared to South Indians (p=0.032) (Table 4).

Figure Analysis

The distribution of anti-HBs titers according to age, gender, and ethnicity among participants who completed the three-dose regimen is illustrated in Figure 1.

Figure 1
Mean anti-HBs titers (mIU/mL) with standard deviation according to gender, age, ethnicity, and geographic group among participants completing the three-dose vaccination regimen.

Discussion

Hepatitis B virus (HBV) infection remains a significant occupational hazard for health care workers (HCWs), particularly in dental settings where exposure to blood and sharps injuries is frequent. The present study evaluated the serological response to hepatitis B vaccination among HCWs and examined factors influencing vaccine-induced immunity.

The overall non-response rate observed in this study was 10.8% among participants who completed the three-dose vaccination regimen, which is consistent with previously reported global estimates of 10–15%¹³-¹⁶. This finding indicates that a proportion of HCWs remain unprotected despite adherence to recommended vaccination schedules, reinforcing the need for routine post-vaccination antibody testing.

A notable finding of this study was the significant influence of ethnicity on vaccine response. All Malaysian participants achieved seroprotection, whereas lower rates were observed among South Indians and North Indians. In addition, Malaysian participants demonstrated significantly higher mean anti-HBs titers compared to Indian participants, and North Indians showed higher titers than South Indians. These variations may be attributed to genetic differences, particularly in human leukocyte antigen (HLA) profiles, which are known to influence immune responsiveness¹³-¹⁶. Although HLA typing was not performed, previous studies have identified specific alleles associated with vaccine non-response¹⁶. Further research incorporating genetic analysis would provide greater insight into these differences.

Age was also found to be a significant determinant of vaccine response. Participants aged ≤30 years exhibited higher seroprotection rates and antibody titers compared to older individuals. This finding is consistent with earlier studies demonstrating stronger immune responses in younger populations¹. The reduced immunogenicity observed in older individuals may be due to age-related decline in immune function, highlighting the importance of early vaccination before occupational exposure.

In contrast to some studies reporting stronger immune responses among females¹⁴, the present study did not demonstrate a significant difference in seroprotection between genders. However, males exhibited higher mean antibody titers. This discrepancy may be related to sample distribution or other unmeasured confounding factors and warrants further investigation.

No statistically significant difference in seroprotection was observed between participants who received two doses and those who completed the three-dose regimen. Although mean antibody titers were higher in the three-dose group, comparable seroprotection rates suggest that partial vaccination may confer some degree of immunity, particularly in younger individuals. However, this finding should be interpreted cautiously, and current vaccination guidelines should not be altered without further large-scale evidence¹⁷. It is well established that anti-HBs antibody levels decline over time, even in individuals who initially achieve adequate seroprotection. Long-term studies have shown that immune memory persists for at least two decades following primary vaccination, even when antibody levels fall below protective thresholds¹⁸,¹⁹. Therefore, routine booster doses are not universally recommended²⁰-²². However, breakthrough infections have been reported, particularly in endemic regions, indicating the need for continued surveillance among high-risk populations²³-²⁵.

Non-genetic factors such as obesity, diabetes, immunosuppression, and vaccine handling have also been associated with reduced vaccine response¹²,¹⁷,²⁶. These factors were largely controlled in the present study through strict exclusion criteria and standardized vaccination protocols. The high vaccination coverage observed (93.5%) reflects effective institutional policies and is higher than rates reported in earlier Indian studies²⁷.

For individuals who fail to respond to the primary vaccine series, the Advisory Committee on Immunization Practices (ACIP) recommends a repeat three-dose series or higher-dose regimens, with antibody testing 1–2 months after completion²⁶,²⁸. However, a subset of individuals may remain non-responsive despite revaccination²⁹. Alternative approaches, including intradermal vaccination and third-generation vaccines containing pre-S1 and pre-S2 antigens, have shown promising results³⁰. In such cases, hepatitis B immunoglobulin remains essential following occupational exposure.

Despite these measures, gaps in awareness and adherence to vaccination protocols persist, particularly among non-professional HCWs. This underscores the importance of continuous education, regular monitoring, and strict implementation of infection control policies³¹-³³.

The present study has certain limitations. Anti-HBc status was not assessed, which could have identified prior HBV infection. Additionally, the study population was predominantly composed of young female students, limiting generalizability. Factors such as body mass index and HLA profiling were also not evaluated, which may have influenced vaccine response.

Overall, the findings of this study emphasize the importance of post-vaccination serological assessment and support the implementation of targeted strategies to ensure adequate protection among HCWs.

Conclusion

Within the limitations of this study, hepatitis B vaccination was found to provide substantial seroprotection among health care workers; however, a notable proportion (10.8%) remained non-seroprotected despite completing the recommended three-dose regimen. No significant differences in seroprotection were observed between genders or between two- and three-dose vaccination schedules. In contrast, age and ethnicity were identified as significant determinants of vaccine response, with younger individuals and Malaysian participants demonstrating higher seroprotection rates and antibody titers.

These findings highlight the importance of routine post-vaccination serological assessment among HCWs to identify non-responders. Targeted strategies, including revaccination and enhanced monitoring, are essential to ensure adequate protection in high-risk populations, particularly in settings with increased occupational exposure.

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• ³³ Chae C, Tak S. Estimated impact of the national hepatitis B immunization program on acute viral hepatitis B among adolescents in Republic of Korea. Osong Public Health Res Perspect. 2023 Apr;14(2):138-45. doi: 10.24171/j.phrp.2022.0321.
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• Data Availability
  The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.
• Ethics Statement
  This study was conducted in accordance with the Declaration of Helsinki. Ethical approval was obtained from the Institutional Ethics Committee (Approval No: 14111).

Edited by

• Editor:
  Dr. Altair A. Del Bel Cury

Data availability

The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.

Publication Dates

• Publication in this collection
  12 June 2026
• Date of issue
  2026

History

• Received
  08 Apr 2024
• Accepted
  26 Sept 2025