Hepatitis B Prevalence and Risk Factors in Punjab, India: A Population-Based Serosurvey

Abstract

Background

The prevalence of hepatitis B virus (HBV) infection in Punjab, India, is unknown. Understanding the statewide prevalence and epidemiology can help guide public health campaigns to reduce the burden of disease and promote elimination efforts.

Methods

A cross-sectional, population-based survey was conducted from October 2013 to April 2014 using a multistage stratified cluster sampling design. All members of selected households aged ≥5 years were eligible. Participants were surveyed for demographics and risk behaviors; serum samples were tested for total antibody to hepatitis B core (total anti-HBc), hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibody (anti-HCV), and HCV RNA. HBsAg-positive specimens were tested for HBV genotype.

Results

A total of 5543 individuals participated in the survey and provided serum samples. The prevalence of total anti-HBc was 15.2% (95% confidence interval [95% CI]: 14.1–16.5) and HBsAg was 1.4% (95% CI: 1.0–1.9). Total anti-HBc positivity was associated with male sex (adjusted odds ratio [aOR] 1.46; 95% CI: 1.21–1.75), older age (aOR 3.31; 95% CI: 2.28–4.79 for ≥60 vs. 19–29 years), and living in a rural area (aOR 2.02; 95% CI: 1.62–2.51). Receipt of therapeutic injections in the past 6 months also increased risk (4–8 injections vs. none; aOR 1.39; 95% CI: 1.05–1.84). Among those positive for total anti-HBc, 10.4% (95% CI: 8.1–13.2) were also anti-HCV positive.

Conclusion

Punjab has a substantial burden of HBV infection. Hepatitis B vaccination programs and interventions to minimize the use of therapeutic injections, particularly in rural areas, should be considered.

Hepatitis B virus (HBV) infection is a global health problem. As of 2019, an estimated 296 million persons worldwide were living with chronic HBV infection, and in the same year, nearly 820,000 deaths were attributable to hepatitis B, primarily from complications of the disease.¹ Among those chronically infected, 20–30% develop complications, such as liver cirrhosis and hepatocellular carcinoma (HCC). Antiviral medications are available to treat HBV infection and can help prevent liver damage and reduce the risk of liver-related deaths.² A variety of effective medications became available in India in the 1990s and early 2000s, although cost was a significant barrier to effective infection control.³

In 2016, the World Health Assembly developed goals for the elimination of viral hepatitis, calling for global reductions in the incidence (by 90%) and mortality (by 65%) of both hepatitis B and hepatitis C by the year 2030.⁴ Hepatitis B vaccination uptake is essential for achieving viral hepatitis elimination. Global vaccination against hepatitis B has been recommended by the World Health Organization (WHO) since 1992, and since then, childhood vaccination practices have reduced the estimated global prevalence of chronic HBV infection in children aged <5 years from 4.7% to 1.3%.⁴ In 2002, India began piloting delivery models for hepatitis B vaccination in select cities and districts; by 2007, efforts were expanded to cover all districts in Punjab and nine other states, and hepatitis B vaccination was included in their national immunization program in 2011.⁵ India's national policy recommends the three-dose vaccine be administered to children at 6, 10, and 14 weeks of age, and birth dose given within 24 h for infants born in medical facilities.⁵ However, as of 2015, birth dose vaccination coverage in India was reportedly only 45%,⁶ and 55% of children aged 12–59 months had been vaccinated.⁷

The global prevalence of chronic HBV infection (positive for hepatitis B surface antigen [HBsAg]) was estimated to be 3.8% in the general population in 2019,¹ and the prevalence in India has been estimated to be between 2% and 8%.⁸ The Northern Indian state of Punjab has a population of 28 million,⁹ and prevalence of HBV infection is unknown, but hepatitis C virus (HCV) burden is known to be higher than in the rest of the country.¹⁰ Given shared transmission routes and risk factors between HBV and HCV, studies are needed to determine the state's burden of hepatitis B. This analysis aims to examine the prevalence of HBV infection in the state of Punjab, India, and to identify the risk factors associated with HBV infection.

Methods

Data Source and Study Population

A cross-sectional seroprevalence survey was conducted in the state of Punjab, India, between October 2013 and April 2014 using a multistage stratified cluster sampling design.¹¹ A target sample of 5500 individuals was selected among those aged ≥5 years using statistical software PASS (NCSS, LLC. 2011 Kaysville, UT, USA). The sample size was selected based on an expected HCV prevalence of 5% to produce 95% confidence intervals (CIs) with a design effect of 2 and a 70% participation rate. Participation in the study was voluntary, and informed consent (for persons aged ≥18 years) or assent paired with parental/guardian permission (for those aged 5–17 years) was obtained for all participants. A questionnaire was administered in person by trained survey teams. Demographic information, medical, surgical, and social history were collected, as well as data on other risk factors associated with viral hepatitis transmission. All risk factor data collected for this study were self-reported or reported by a parent or guardian of children. Participants were also asked for vaccination history. A detailed description of the survey and sampling methods are described elsewhere.¹¹ Study participants were provided pretest counseling and were notified of test results by both telephone and mail within 3 weeks of the interview; if positive for active infection, they were provided post-test counseling and referral to a hepatologist for further care.

Laboratory Methods

Following the interview, a blood sample from each consenting participant was obtained, centrifuged, and the serum aliquoted into cryovials for storage at −80°C. Specimens were shipped to a central laboratory for diagnostic testing (Oncquest laboratories Ltd., Delhi, India). Specimens were first tested for total antibody to hepatitis B core (total anti-HBc) using a Chemiluminescent Microparticle Immunoassay (CMIA) on automated ARCHITECT platform (Abbott Laboratories, IL, USA); those found positive for total anti-HBc were tested for HBsAg by CMIA (Vitros Immunodiagnostic HBsAg ES; Johnson and Johnson Co., New Brunswick, NJ, USA). HBsAg-positive specimens were sequenced to determine the HBV genotype by a method reported previously.¹² In addition, all samples were tested for HCV: those positive for HCV antibody (anti-HCV; Vitros Immunodiagnostic Anti-HCV, Johnson and Johnson Co.) were tested for HCV RNA (COBAS1TaqMan1 HCV Test; Roche, Indianapolis, IN, USA).

The samples collected for this study were also tested for serologic evidence of past infection with hepatitis A virus and hepatitis E virus, but those results are not presented here. The results of the estimated prevalence of HCV infection from this study have been previously reported.¹¹

Statistical Analysis

Data were weighted based on population sizes of wards and villages using 2011 census data, and the weighting was stratified by urban/rural status to be representative for the state of Punjab.⁹ The results are presented as weighted percentages with 95% CI. Bivariate associations for demographic and other risk factors were assessed using chi-square tests for both total anti-HBc and HBsAg, with a significance level of P < .05. All factors significantly associated with total anti-HBc in bivariate analysis were included in a multivariable logistic regression model. The analysis was conducted in SAS version 9.4 (Cary, NC, USA).

Results

A total of 5543 individuals from 1399 households agreed to participate and were included in the analysis. Most participants were female (n = 3005; 53.8%), median age was 35 years (interquartile range 21–50), and most lived in a rural setting (n = 3460; 62.4%; Table 1). A majority of the population lived in households earning <20,000 rupees monthly (n = 4546; 81.9%; equivalent to approximately 300 U.S dollars), and 12.5% had a graduate-level education.

Table 1.

Prevalence of Anti-HBc and HBsAg by Demographic and Risk Factor Characteristics, Punjab, India, October 2013 to April 2014.

Characteristic	Sample, n	Weighted, %	Total Anti-HBc+ , % (95% CI) n = 834	Chi-square P value	HBsAg+ , % (95% CI) n = 78	Chi-square P value
Overall	5543	100.0	15.2 (14.1, 16.5)		1.4 (1.0, 1.9)
Sex
Female	3005	53.8	13.6 (12.2, 15.0)	0.0001	1.0 (0.7, 1.5)	0.01
Male	2538	46.2	17.2 (15.6, 18.9)		1.9 (1.3, 2.7)
Age group (years)
5–18	1107	20.2	3.8 (2.6, 5.6)	<0.0001	0.6 (0.2, 1.3)	<0.001
19–29	1024	18.3	10.4 (8.4, 12.7)		1.3 (0.8, 2.3)
30–39	998	18.0	12.8 (10.6, 15.4)		1.1 (0.6, 2.2)
40–49	870	15.7	17.6 (15.0, 20.6)		0.6 (0.2, 1.4)
50–59	721	13.0	21.1 (17.8, 24.7)		2.8 (1.8, 4.4)
60+	823	14.9	32.0 (28.6, 35.6)		2.6 (1.6, 4.1)
Region
Urban	2083	37.6	9.5 (8.3, 10.9)	<0.0001	0.8 (0.5, 1.3)	<0.001
Rural	3460	62.4	18.7 (17.0, 20.5)		1.8 (1.3, 2.5)
Marital status
Never married	1708	30.8	6.3 (5.1, 7.8)	<0.0001	1.0 (0.6, 1.8)	0.26
Married	3512	63.3	18.6 (17.1, 20.2)		1.6 (1.1, 2.1)
Divorced/widowed	323	5.9	26.1 (21.5, 31.4)		1.8 (0.8, 4.1)
Household income, monthly
<20,000 rupees	4546	81.9	15.9 (14.6, 17.4)	0.01	1.5 (1.1, 2.1)	0.21
≥20,000 rupees	997	18.1	12.1 (9.8, 14.7)		0.9 (0.4, 1.9)
Education
Never/primary school	2114	37.7	19.6 (17.6, 21.8)	<0.0001	1.5 (1.0, 2.2)	0.78
Middle/secondary	2735	49.8	13.1 (11.8, 14.6)		1.5 (1.0, 2.1)
Graduate/above	694	12.5	10.4 (8.2, 13.1)		1.1 (0.4, 2.6)
Vaccination for any hepatitis
Yes	1903	33.4	10.2 (8.8, 11.9)	<0.0001	0.5 (0.2, 0.9)	<0.001
No	3381	62.2	17.9 (16.3, 19.7)		1.9 (1.4, 2.6)
Don't know	259	4.4	14.9 (10.7, 20.4)		1.4 (0.5, 3.8)
Number of injections, last 6 months
0	3639	65.2	13.2 (11.9, 14.6)	<0.0001	0.9 (0.6, 1.4)	<0.001
1–3	1155	21.1	16.0 (13.8, 18.6)		2.3 (1.5, 3.4)
4–8	461	8.3	23.9 (18.5, 30.3)		1.3 (0.6, 2.9)
>8	288	5.4	23.5 (19.5, 27.9)		3.9 (2.0, 7.3)
Last injection administered by
Medical doctor	1149	20.4	12.4 (10.3, 14.8)	0.001	1.2 (0.7, 2.1)	0.64
Registered nurse/pract.	3090	56.9	16.8 (15.2, 18.4)		1.5 (1.1, 2.1)
Self/family/unlicensed	124	2.1	22.5 (15.2, 18.4)		2.4 (0.8, 7.1)
Other/unknown	106	1.9	12.3 (7.2, 21.1)		0.3 (0.0, 4.0)
N/A	1074	18.7	13.2 (11.1, 15.7)		1.2 (0.6, 2.7)
Number of times donating blood, ever
0	4808	86.5	14.8 (13.6, 16.1)	0.03	1.3 (1.0, 1.8)	0.37
1–3	528	9.8	19.3 (16.0, 23.0)		2.1 (1.1, 3.8)
>3	207	3.7	14.4 (10.0, 20.2)		1.0 (0.3, 3.6)
Blood transfusion, ever
Yes	368	6.5	20.4 (16.4, 25.1)	0.01	1.4 (0.6, 3.4)	0.97
No	5175	93.5	14.9 (13.7, 16.2)		1.4 (1.0, 1.9)
STI, ever (among adults)
Yes	278	5.8	16.8 (12.6, 22.1)	0.66	0.6 (0.2, 2.4)	0.01
No	4235	94.2	18.0 (16.6, 19.4)		1.7 (1.3, 2.2)
Injection drug use, ever
Yes	5	0.1	20.2 (3.7, 62.6)	0.76	–	–
No	5538	99.9	15.2 (14.0, 16.5)		1.4 (1.0, 1.9)
Received a tattoo
Yes	479	8.6	20.4 (16.6, 24.8)	0.004	2.5 (1.4, 4.4)	0.04
No	5064	91.4	14.7 (13.5, 16.0)		1.3 (1.0, 1.8)
Dialysis, ever
Yes	26	0.4	12.0 (4.2, 30.0)	0.68	–	–
No	5517	99.6	15.2 (14.1, 16.5)		1.4 (1.1, 1.9)
Incarcerated, ever
Yes	89	1.7	32.5 (23.6, 43.0)	<0.0001	5.6 (2.4, 12.5)	<0.001
No	5454	98.3	14.9 (13.8, 16.2)		1.3 (1.0, 1.8)

anti-HBc, antibody to hepatitis B core; HBsAg, hepatitis B surface antigen; CI, confidence interval; STI, sexually transmitted infection; pract, practitioner.

HBV Prevalence and Risk Factors

The overall prevalence of total anti-HBc was 15.2% (95% CI: 14.1–16.5). Total anti-HBc prevalence was higher among males (17.2%) than females (13.6%) and increased with age, from a low of 3.8% among those aged 5–18 years to 32.0% among those aged ≥60 years (Table 1). When stratified by age and sex, males aged ≥60 years had the highest prevalence among all sex/age groups at 33.9% (Figure 1). Rural regions had higher prevalence, and districts in the south also experienced higher prevalence (Figure 2). In bivariate analysis, the prevalence of total anti-HBc was associated with marital status, household income, education, vaccination history, number of therapeutic injections in the last 6 months, the administrator of last injection, number of times ever donated blood, ever receiving a blood transfusion, receipt of a permanent tattoo, and incarceration. After adjusting for covariates, associations remained for rural regions (adjusted odds ratio [aOR] 2.02; 95% CI: 1.62–2.51) and receipt of 4–8 injections in the past 6 months compared with none (aOR 1.39; 95% CI: 1.05–1.84; Table 2).

Figure 1.

Prevalence of total anti-HBc and HBsAg positivity by age and sex, Punjab, India, October 2013 to April 2014. anti-HBc, hepatitis B core antibody; HBsAg, hepatitis B surface antigen.

Figure 2.

Prevalence of total anti-HBc positivity by district, Punjab, India, October 2013 to April 2014.

Table 2.

Association of Anti-HBc Positivity With Selected Variables, Punjab, India, October 2013 to April 2014.

Characteristic	Total anti-HBc+ , % (95% CI)	Unadjusted , odds ratio (95% CI)	Adjusted∗ , odds ratio (95% CI)
Sex
Female	13.6 (12.2, 15.0)	1	1
Male	17.2 (15.6, 18.9)	1.32 (1.15, 1.53)	1.46 (1.21, 1.75)
Age group (years)
5–18	3.8 (2.6, 5.6)	0.35 (0.22, 0.54)	0.34 (0.20, 0.58)
19–29	10.4 (8.4, 12.7)	1	1
30–39	12.8 (10.6, 15.4)	1.27 (0.93, 1.73)	1.24 (0.84, 1.81)
40–49	17.6 (15.0, 20.6)	1.85 (1.37, 2.49)	1.75 (1.20, 2.55)
50–59	21.1 (17.8, 24.7)	2.31 (1.73, 3.08)	2.11 (1.45, 3.07)
60+	32.0 (28.6, 35.6)	4.07 (3.11, 5.32)	3.31 (2.28, 4.79)
Region
Urban	9.5 (8.3, 10.9)	1	1
Rural	18.7 (17.0, 20.5)	2.19 (1.80, 2.66)	2.02 (1.62, 2.51)
Marital status
Never married	6.3 (5.1, 7.8)	1	1
Married	18.6 (17.1, 20.2)	3.38 (2.67, 4.28)	1.06 (0.71, 1.58)
Divorced/separated/widow	17.7 (4.7, 48.7)	5.25 (3.72, 7.41)	1.08 (0.66, 1.76)
Household income
<20,000 rupees	15.9 (14.6, 17.4)	1	1
≥20,000 rupees	12.1 (9.8, 14.7)	0.73 (0.56, 0.93)	0.86 (0.66, 1.12)
Education
Never/primary school	19.6 (17.6, 21.8)	1	1
Middle/secondary	13.1 (11.8, 14.6)	0.62 (0.53, 0.73)	0.86 (0.71, 1.05)
Graduate/above	10.4 (8.2, 13.1)	0.47 (0.36, 0.63)	0.84 (0.60, 1.19)
Vaccination for any hepatitis
Yes	10.2 (8.8, 11.9)	1	1
No	17.9 (16.3, 19.7)	1.92 (1.58, 2.32)	1.11 (0.89, 1.38)
Don't know	14.9 (10.7, 20.4)	1.54 (1.02, 2.32)	1.04 (0.69, 1.59)
Number of injections, last 6 months
0	13.2 (11.9, 14.6)	1	1
1–3	16.0 (13.8, 18.6)	1.26 (1.02, 1.54)	1.08 (0.86, 1.35)
4–8	23.9 (18.5, 30.3)	2.02 (1.56, 2.61)	1.39 (1.05, 1.84)
>8	23.5 (19.5, 27.9)	2.07 (1.48, 2.89)	1.29 (0.90, 1.86)
Last injection administered by
Medical doctor	12.4 (10.3, 14.8)	1	1
Registered nurse/pract.	16.8 (15.2, 18.4)	1.43 (1.14, 1.79)	1.09 (0.86, 1.39)
Self/family/unlicensed	22.5 (15.2, 18.4)	2.06 (1.21, 3.53)	1.27 (0.72, 2.25)
Other/unknown	12.3 (7.2, 21.1)	0.99 (0.53, 1.88)	0.86 (0.46, 1.59)
N/A	13.2 (11.1, 15.7)	1.08 (0.81, 1.43)	1.14 (0.84, 1.55)
Number of times donating blood, ever
0	14.8 (13.6, 16.1)	1	1
1–3	19.3 (16.0, 23.0)	1.37 (1.08, 1.74)	0.96 (0.73, 1.25)
>3	14.4 (10.0, 20.2)	0.97 (0.64, 1.47)	0.85 (0.55, 1.33)
Blood transfusion, ever
Yes	20.4 (16.4, 25.1)	1	1
No	14.9 (13.7, 16.2)	0.68 (0.51, 0.90)	0.79 (0.58, 1.07)
Received a tattoo
Yes	20.4 (16.6, 24.8)	1	1
No	14.7 (13.5, 16.0)	0.68 (0.52, 0.88)	0.85 (0.63, 1.16)
Incarcerated, ever
Yes	32.5 (23.6, 43.0)	1	1
No	14.9 (13.8, 16.2)	0.36 (0.23, 0.58)	0.72 (0.43, 1.21)

∗Adjusted for all variables associated with total anti-HBc in bivariate analysis.

anti-HBc, antibody to hepatitis B core; CI, confidence interval; pract, practitioner.

The overall prevalence of HBsAg was 1.4% (95% CI: 1.0–1.9). The prevalence was higher among males (1.9%) than females (1.0%) and varied by age, with the highest prevalence observed among those aged 50–59 years (2.8%; Table 1). As with total anti-HBc, the prevalence of HBsAg was higher in rural (1.8%) than in urban (0.8%) regions. In addition, in bivariate analysis, significant associations were found for vaccination history, number of injections in the past 6 months, ever having a sexually transmitted infection, and ever being incarcerated. Overall, 0.4% (95% CI: 0.2–0.7) reported ever having been diagnosed with hepatitis B. Among HBsAg-positive persons, 28.5% (95% CI: 18.4–41.3) had been told by a healthcare worker they have liver disease or jaundice. Also among HBsAg-positive persons, 37 had genotype testing, with 31 (83.3%) having genotype D and 2 (5.4%) having genotype A; 4 (10.8%) had no genotype detected.

Overall, 33.4% (95% CI: 31.7–35.2) self-reported that they had been vaccinated against hepatitis B, with the highest percentage among those aged 5–10 years (78.3%; Figure 3). In multivariable analysis, total anti-HBc positivity was not associated with self-reported vaccination status.

Figure 3.

Self-report of hepatitis B vaccination by age group, Punjab, India.

Coinfections

Among those who tested positive for total anti-HBc, 10.4% (95% CI: 8.1–13.2) also tested anti-HCV positive, and 7.7% (95% CI: 5.7–10.3) tested positive for HCV RNA. Among the 78 participants with chronic HBV infection, 2 (2.6%) tested positive for anti-HCV, and 1 (1.3%) tested positive for HCV RNA (unweighted). Conversely, among those positive for anti-HCV, 44.4% (95% CI: 36.5–52.5) tested positive for total anti-HBc and 0.3% (95% CI: 0.0–2.5) tested positive for HBsAg. Among 138 participants with chronic HCV infection, 63 (45.7%) tested positive for total anti-HBc and 1 (0.7%) tested positive for HBsAg (unweighted). Among those with exposure to both HBV and HCV, 20.4% (95% CI: 12.7–31.0) reported ever being diagnosed with viral hepatitis.

Discussion

This study presents the first comprehensive prevalence and risk factor assessment for hepatitis B in Punjab, India. Overall, the weighted prevalence of exposure to HBV (total anti-HBc positive) was 15.2%, and active or chronic infection (HBsAg positive) was 1.4%. This rate of chronic infection is lower than the 3% reported for India nationwide⁸ and, relative to global prevalence, is considered low endemicity (defined as <2.0% in a systematic review of 161 countries).¹³ Nonetheless, given Punjab's population of 28 million people,⁹ this equates to approximately 400,000 persons actively infected with HBV in the state. Individuals with chronic HBV infection are at increased risk for liver cirrhosis, liver cancer, or liver failure,¹⁴ and therefore, this estimate constitutes a considerable public health burden.

The association of HBV infection with male sex and older age is well documented, and both markers are associated with a higher risk of liver-related poor health outcomes, including HCC.² In this analysis, while the prevalence of total anti-HBc positivity increased steadily with age, current HBV infection (HBsAg positivity) was most prevalent among those aged 50–59 years. This birth cohort had a prevalence nearly fivefold higher than those aged 40–49 years (2.8% vs 0.6%). The relatively high rate of HBsAg positivity among those aged ≥50 years relative to their total anti-HBc prevalence suggests higher transmission rates during birth or early childhood for these birth cohorts.

The prevalence of HBV infection differed by urban/rural geography and was higher in southern districts. This association was also found for HCV infections and could be attributable to unsafe injection practices among unqualified practitioners in rural areas of Punjab.¹¹ This is supported by our findings; in bivariate analysis, a higher total anti-HBc positivity prevalence was found among those who had their last injection administered by an unlicensed practitioner, family member, or themselves. The injection administrator was also associated with geographical area, as injection by an unlicensed practitioner was reported more often among those in rural than urban areas. Unsafe injection practices are a risk factor for both HBV and HCV infection, and a study conducted in the year 2000 showed they accounted for 30% of new HBV infections globally.¹⁵ However, with vaccination efforts and decreases in unsafe injections, global data showed a 91% reduction in injection-related HBV infections in 2010.¹⁶ Public awareness and educational campaigns should be considered to ensure this reduction is experienced in Punjab and to limit unsafe injections by untrained persons.

Among those with past or present HBV infection, 10% also had a history of HCV infection. Given the similar transmission routes and risk factors for HBV and HCV, this is not unexpected.¹⁷ However, co-infection with HBV and HCV affords a greater risk of cirrhosis, decompensated liver disease, and HCC and more complicated treatment.¹⁸ Monitoring of co-infected persons is necessary to ensure effective therapies for the long-term health of patients.

Among the samples tested for HBV genotyping, only genotypes A and D were discovered, with the latter making up the majority (83%) of cases. This is consistent with other studies documenting these two genotypes in various areas of mainland India.¹⁹ Studies have shown a correlation of these genotypes with treatment effectiveness; HBV genotype A has been shown to respond more effectively to interferon-based treatments, whereas genotype D has a poor response.²⁰

Vaccine coverage was highest among those aged 5–10 years at nearly 80% and decreased steadily with age. This corresponds with the rollout of HBV vaccination in India beginning in 2002⁵ and is promising for the younger population in Punjab, given a national 2017–2018 study reporting 38% vaccination coverage among children born after the introduction of the vaccine. Another study among children conducted nationally in 2015–2016 reported higher rates of vaccination in the state of Punjab,⁷ which is supported by this analysis, and could explain lower rates of HBV infection in Punjab compared with HCV infection.¹¹ Approximately 90% of infants infected with HBV perinatally develop chronic infection,²¹ although administration of birth dose hepatitis B vaccination is 75% effective in preventing perinatal transmission,²² and WHO recommends administration as soon as possible after birth but preferably in the first 24 h.²³ Thus, further promotion and facilitation of the immunization program in Punjab is essential to move India along the road to hepatitis B elimination as guided by WHO. A small number of persons self-reporting hepatitis B vaccination tested positive for HBsAg in this survey, and the finding that anti-HBc was not associated with vaccination status in multivariable analysis could be an indication of recall bias or incomplete three-dose vaccination.

This analysis was subject to several limitations. With respect to risk factors for HBV infection, the cross-sectional design of this analysis prevents causal association. Infection could have occurred at any time since birth, possibly preceding the risk factors evaluated. The survey was powered to determine the prevalence estimates for HCV rather than HBV infection, and weighting could not be accurately applied for all variables, notably for genotyping and coinfections among chronically infected persons. This inhibits regionally representative prevalence estimates, and proportions thereof should be interpreted with caution. Lack of data for HBV DNA and hepatitis B surface antibody prevents distinction between recovered HBV and occult HBV among anti-HBc-positive/HBsAg-negative persons. HBeAg and anti-HBe testing was not conducted. Liver function testing was not performed, so we could not assess the progression or severity of the liver disease. Participants were also not asked if they had ever been treated for hepatitis B. The in-person implementation of the survey could also have led to a social desirability bias, as participants may not have been forthright about disclosure of stigmatizing behaviors such as injection drug use. The very small proportion of participants who reported injection drug use contradicts reports of increasing trends in the country²⁴ and makes association with HBV infection, or lack thereof, difficult to interpret. Collection of risk behavior by self-report can introduce recall bias, particularly for lifetime assessments such as number of blood donations or vaccinations. Finally, sampling multiple persons per household could have caused selection bias, whereby members of the same household exhibited similar risk patterns and behaviors, affecting generalizability to the greater population. Despite these limitations, as the first study to report statewide prevalence of HBV infection in Punjab, these findings are important for understanding the public health burden of HBV infection in the state.

In conclusion, the state of Punjab, India, has a low positivity prevalence for chronic HBV infection on a global scale, lower than the rest of India. However, given its large population, the burden of HBV infection in Punjab is still considerable. Unsafe injection practices were identified as associated with transmission, suggesting more can be done to curb this behavior, especially in rural areas and by strict control on practices of unlicensed practitioners. Promotion and adherence to existing vaccination programs including birth dose vaccinations could help to reduce incident infections in the state.

Credit authorship contribution statement

Shaun Shadaker: methodology, formal analysis, data curation, writing – original draft, writing – review & editing, visualization. Ajit Sood: conceptualization, methodology, writing – review & editing, visualization. Francisco Averhoff: methodology, writing – original draft, writing – review & editing, visualization. Anil Suryaprasad: writing – review & editing. Subodh Kanchi: writing – review & editing. Vandana Midha: writing – review & editing. Saleem Kamili: methodology, writing – original draft, writing – review & editing. Muazzam Nasrullah: writing – original draft, writing – review & editing. Adam Trickey: writing – review & editing. Ravinder Garg: writing – review & editing. Parmod Mittal: writing – review & editing. Suresh K Sharma: writing – review & editing. Peter Vickerman: writing – review & editing. Paige A Armstrong: writing – original draft, writing – review & editing.

Conflicts of interest

S.K. and M.N. are, or have been, employees of Merck. A.S. has also received funding from Merck. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the article.

Funding

This population survey was sponsored by MSD Pharmaceuticals India Private Limited, a subsidiary of Merck & Co. Inc., Kenilworth, NJ, USA; sponsoring corporations do not contribute to writing of manuscripts.

Disclaimer

The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the US Centers for Disease Control and Prevention. The use of trade names and commercial sources is for identification only and does not imply endorsement by the Centers for Disease Control and Prevention, the Public Health Service, or the US Department of Health and Human Services.

Ethical approval

Ethical approval for this study was obtained from the institutional review board at Dayanand Medical College, Ludhiana, India, and the Merck Investigator Initiated Study Protocol-Review Committee; protocol was also reviewed and approved by the Centers for Disease Control & Prevention.