
==== Front
BMC Infect Dis
BMC Infect Dis
BMC Infectious Diseases
1471-2334
BioMed Central London

9846
10.1186/s12879-024-09846-4
Research
Immunization status and factors influencing hepatitis B vaccination of preterm infants in three provinces of China, 2019 to 2021
Huang Li-fang 123
Huang Ao-di 23
Zhang Xue 23
Tang Lin 23
An Jing 4
Li Jun 5
Zheng Hui 23
Yin Zun-dong 23
Wang Fu-zhen wangfz@chinacdc.cn

23
1 Department of National Immunization Program, Fujian Provincial Center for Disease Control and Prevention, Fuzhou, 350012 China
2 https://ror.org/04wktzw65 grid.198530.6 0000 0000 8803 2373 Chinese Center for Disease Control and Prevention, National Immunization Program, Beijing, 100050 China
3 https://ror.org/04wktzw65 grid.198530.6 0000 0000 8803 2373 National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, Chinese Center for Disease Control and Prevention, Beijing, 102200 China
4 https://ror.org/05tfnan22 grid.508057.f Gansu Provincial Center for Disease Control and Prevention, Lanzhou, 730010 China
5 https://ror.org/01479r334 grid.418504.c Henan Provincial Center for Disease Control and Prevention, Zhengzhou, 450018 China
10 9 2024
10 9 2024
2024
24 95114 11 2023
30 8 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Background

Premature infants have less physiologic reserve and often delayed vaccination compared to full-term infants. The birth dose of hepatitis B vaccine (HepB-BD) is an essential measure to achieve the goal of "zero infections" of hepatitis B virus in all newborns. However, there are few investigations of hepatitis B vaccination of preterm infants, leading to uncertainty of coverage and insufficient knowledge of factors influencing timely vaccination of this important population.

Methods

We obtained hepatitis B vaccine (HepB) vaccination histories of premature infants born during 2019–2021 in three provinces from the respective provincial immunization information systems. Extracted data included date of birth, sex, region, and dates of HepB administration. We conducted descriptive analyses that included basic characteristics of the study subjects, HepB-BD administration, and full-series HepB vaccination. Factors potentially influencing HepB-BD and full series vaccination were analyzed by logistic regression.

Results

There were 1623 premature infants included in the analytic data set. Overall HepB-BD coverage was 71.41%; coverage among premature infants born to mothers with unknown hepatitis B surface antigen (HBsAg) status was 69.57%; coverage was higher at county-level-and-above hospitals (72.02%) than hospitals below county level (61.11%). Full-series HepB coverage was 94.15%; full-series coverage among preterm infants weighing less than 2000 g at birth was 76.92%. Logistic regression showed that the HepB-BD vaccination rate was positively associated with being born to an HBsAg-positive mother and being preterm with high birth weight. Regression analysis for factors influencing full-series HepB coverage showed that being born prematurely was positively associated with full-series coverage and being premature with a very low birth weight was negatively associated with full-series coverage.

Conclusions

HepB-BD coverage levels in three provinces of China were less than the target of 90%, especially among premature infants born to mothers with unknown HBsAg status and at hospitals below the county level. Screening of pregnant women should be a universal normal standard. Hepatitis B vaccination training should be strengthened in hospitals to improve the HepB-BD vaccination rate of premature infants and to effectively prevent mother-to-child transmission of hepatitis B virus.

Keywords

Preterm infants
HepB-BD vaccination
Full-series HepB vaccination
Influencing factors
issue-copyright-statement© BioMed Central Ltd., part of Springer Nature 2024
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pmcBackground

Hepatitis B is a serious infectious disease caused by hepatitis B virus (HBV) and is a global public health problem. China has a moderate prevalence of hepatitis B [1], with an estimated 70 million people living with HBV in 2017 and an overall population prevalence of 5%-6% [2]. To achieve the goal of eliminating hepatitis B as a public health problem, in 2017, WHO proposed to eliminate mother to child transmission of hepatitis B virus by 2030 [3]. In June 2022, WHO officially released the Global Health Sector Strategies on, Respectively, HIV, Viral Hepatitis and Sexually Transmitted Infections for the Period 2022–2030 [4]. This strategy recognizes that hepatitis B vaccine (HepB) is the most effective measure to realize the goal of “zero infections” of hepatitis B virus in newborns and must be administered to all newborn infants [3, 5].

Fifteen million babies are born prematurely every year in the world, representing 11.1% of the global birth cohort [6]. In China, 1.2 million premature babies are born every year, for a 7% preterm birth rate [7]. Premature infants are susceptible to HBV infection during childbirth and need to be protected with HepB vaccination, just as do full-term infants. Premature infants generally have a lower birth weight than full-term infants. The National Immunization Program Childhood Immunization Procedures and Instructions (2021 Edition) recommends that the first dose of HepB should be administered as soon as possible after birth to infants weighing less than 2000 g who are born to HBsAg positive or unknown status mothers, and an additional three doses of HepB should be administered subsequently – a dose at 1 month, 2 months, and 7 months of age [8]. Premature and low-birth-weight infants have less physiologic reserve and lower ability to adapt to stressors than full-term infants [9], and their resistance to infections is relatively weak.

To fully realize the goal of eliminating mother-to-child transmission of HBV, more attention should be paid to HepB vaccination of premature infants. However, there are few investigations of HepB vaccination of premature infants in China, leading to uncertainty of coverage and insufficient knowledge of factors influencing timely vaccination of this important population. We obtained vaccination histories of children born during 2019–2021 in three province of China and conducted descriptive and influencing-factor analyses to provide an evidence basis for improving hepatitis B vaccination rates of premature infants.

Methods

We conducted a retrospective cohort study of premature infants born during 2019– 2021 to determine their rate of timely birth dose of hepatitis B vaccine and factors influencing timeliness rates.

Setting, data, and subjects

We selected three provinces to be exemplar provinces of eastern, central, and western China, representing the spectrum of socioeconomic development: Fujian Province in the east, Henan Province in central China, and Gansu Province in the west. In each province, two counties that participate in the province’s immunization information system (IIS) and the Maternal and Child Information System were selected for study: Shishi and Hui'an counties of Quanzhou City, Fujian Province; Yuyang and Huaiyang districts of Xinxiang City and Zhoukou City, Henan Province; and Ganzhou District of Zhangye City and Tongwei County of Dingxi City, Gansu Province.

All infants born during the study period were screened for inclusion using data from the two information systems. IIS-Extracted data on the infants included date of birth, sex, region, and dates of HepB vaccination. We matched infant IIS data with maternal information in the maternal and child system: hospital of birth, birth weight, gestational age, birth number, maternal age, and maternal HBsAg status. Subject inclusion criteria were having birthing hospital data, including gestational age at birth and birth weight; eventual receipt of at least 3 doses of HepB; dose and vaccination timing recorded in proper chronological sequence; inter-dose intervals in line with minimum intervals recommended by the National Immunization Program Children Immunization Procedures and Instructions (2021 Edition) [8] that the interval between HepB1 and HepB2 is ≥ 28d and the interval between HepB2 and HepB3 is ≥ 60d. Subject exclusion criteria were unknown gestational age at birth or birth weight; receipt of fewer than 3 doses of HepB; dose and vaccination timing recorded in a non-chronological sequence; and inter-dose intervals not in line with minimum intervals recommended by the National Immunization Program Children Immunization Procedures and Instructions (2021 Edition).

Statistical analysis

We conducted descriptive analyses of the study subjects’ HepB-BD and full-series HepB coverage levels. The HepB-BD vaccination rate was the number of neonates receiving HepB-BD divided by the number of neonates born × 100%. We considered HepB-BD vaccination to be HepB administration < 24 h after birth, although vaccination on the day after birth was also accepted as timely vaccination for this study. Full series HepB coverage was the number of infants receiving three doses of HepB within 12 months of age divided by the number of births × 100%. Factors influencing the timely birth dose rate and the full series vaccination rate were analyzed using logistic regression.

All analyses were conducted by using SAS software (version9.4, SAS Institute, Inc., Cary, NC, USA). Two-sided P values < 0.05 were considered statistically significant.

Results

There were 1623 premature infants that met inclusion criteria and were included in the final analytic data set (Fig. 1). Table 1 shows HepB-BD and full series coverage by subject characteristics. The sex ratio was 1.37 (939/684) and birth weight ranged from 400-5800 g, with a median of 2660 g (IQR: 2350-3000 g). The HepB-BD vaccination rate of preterm infants was 71.41% (1159/1623), and the HBsAgs screening rate of the mothers during pregnancy was 91.49% (1485/1623). HepB-BD vaccination was higher at county-level-and-above hospitals than hospitals below the county level. HepB-BD vaccination of premature infants born to HBsAg positive mothers was higher than that of preterm infants born to HBsAg negative mothers, but HepB-BD vaccination of premature infants born to mothers with unknown HBsAg status was lower than that of preterm infants born to HBsAg negative mothers. HepB-BD vaccination was higher in preterm infants weighing 2.5 kg or more. The HepB-BD vaccination rate was highest among infants born around 37 (32–36) weeks gestation.Fig. 1 Study flow chart

Table 1 HepB-BD and full-series HepB vaccination rates for premature infants in three provinces of China, 2019 through 2021

Variable	N	HepB-BD vaccination rate	Full-series HepB vaccination rate	
Child variables		n (%)	χ2	P	n (%)	χ2	P	
Sex	
 Male	939	674 (71.78)	0.15	0.701	881 (93.82)	0.42	0.516	
 Female	684	485 (70.91)			647 (94.59)			
Gestational age at birth	
 < 28 weeks	14	10(71.43)		< 0.001	14 (100)		< 0.001	
 28-32 weeks	104	45(43.27)			90(86.54)			
 32-36 weeks	1505	1104 (73.36)			1424 (94.62)			
Year of birth	
 2019	285	214 (75.09)	2.37	0.31	256 (89.82)	25.62	< 0.001	
 2020	571	401 (70.23)			527 (92.29)			
 2021	767	544 (70.93)			745 (97.13)			
Province of birth	
 Fujian	1143	829 (72.53)	15.65	< 0.001	1059 (92.65)	16.02	< 0.001	
 Henan	448	229 (66.74)			437 (97.54)			
 Gansu	32	31 (96.88)			32 (100)			
Birthing hospital	
 Below county level	90	55 (61.11)	4.95	0.026	79 (87.78)	7.01	0.008	
 County level or above	1533	1104 (72.02)			1449 (94.52)			
Birth parity	
 1	529	360 (68.05)	6.54	0.165	514 (97.16)	25.35	< 0.001	
 2	641	479 (74.73)			607 (94.70)			
 3	310	219 (70.65)			277 (89.35)			
 ≥ 4	139	98 (70.50)			126 (90.65)			
 unknown	4	3 (75.00)			4 (100)			
Birth weight (g)	
 ≥ 2500	1070	861 (80.47)	214.87	< 0.001	1019 (95.23)	7.98	0.018	
 2000–2500	434	275 (63.36)			402 (92.63)			
 < 2000	119	23 (19.33)			107 (76.92)			
Maternal variables	
Mother’s age	1493							
 15–29	699	516 (73.81)	5.97	0.050	656(93.85)	0.40	0.817	
 30–39	744	535 (71.91)			704(94.62)			
 40–51	50	29 (58.00)			47(94.00)			
Mother's HBsAg status	
 Negative	1323	912 (68.93)	41.91	< 0.001	1245 (94.10)	1.18	0.554	
 Positive	162	151 (93.21)			155 (95.68)			
 Unknown	138	96 (69.57)			128 (92.75)			
 Total	1623	1159 (71.41%)			1528 (94.15%)			

The full-series HepB vaccination rate was 94.15% (1528/1623). The number of premature infants born in hospitals at or above the county level was higher than the number born in hospitals below the county level. The lower the birth weight, the lower the full coverage rate among preterm infants. The full-series coverage rate of preterm infants weighing less than 2000 g at birth was 76.92%. Full-series HepB coverage was highest in premature infants with gestational age less than 28 weeks and 32–36 weeks.

Table 2 shows logistic regression analyses for factors associated with HepB-BD and full-series vaccination. The HepB-BD vaccination rate was positively associated with being born to an HBsAg positive mother and being preterm with high birth weight. Regression analysis for factors influencing full-series HepB coverage showed that being born in 2021 (compared with 2019) was positively associated with full-series coverage, being born prematurely was positively associated, and being premature with a very low birth weight was negatively associated with full-series HepB coverage (compared with having normal birth weight). Table 2 Logistic regression analysis of factors influencing HepB-BD vaccination and full-series HepB vaccination in premature infants

Variable	Timely HepB-BD vaccination	Full-series HepB vaccination	
OR	95%CI	P	OR	95%CI	P	
Birth weight(g)	
 ≥ 2500	1			1			
 2000–2500	0.41	0.32–0.52	0.001	0.63	0.40–1.00	0.917	
 < 2000	0.05	0.03–0.08	< 0.001	0.42	0.22–0.82	0.054	
Year of birth	-	-	-				
 2019				1			
 2020				1.37	0.84–2.25	0.088	
 2021				3.90	2.20–6.94	< 0.001	
Mother's HBsAg status				-	-	-	
 negative	1						
 positive	7.00	3.43–14.29	< 0.001				
 unknown	1.20	0.77–1.87	0.386				

Discussion

Hepatitis B vaccine is known to be safe and immunogenic in premature infants and is widely recommended for use in premature infants throughout the world. To achieve the WHO goal of eliminating the threat of viral hepatitis by 2030, in November 2017, the National Health and Family Planning Commission and 11 other departments jointly issued the "Chinese Viral Hepatitis Prevention and Control Plan (2017–2020)" [10], which proposed that the HepB-BD vaccination rate among newborn infants should remain above 90% in 2020. Overall, full-series HepB coverage continues to be greater than 95%. In December 2022, the National Health Commission issued the Action Plan for the Elimination of Mother to Child Transmission of AIDS, Syphilis, and Hepatitis B (2022–2025) [11], which proposed that the rate of mother-to-child transmission of hepatitis B virus should be reduced to 1% or less by 2025, and that the HepB-BD vaccination rate among premature infants born to HBsAg positive mothers should be above 95%.

A study by Miao Ning and colleagues in China in 2020 found that HepB-BD coverage among children aged 1–4 years in China was 91.54% [12], HepB-BD coverage among newborn in Luoyang in 2014 was 93.77% [13]. Our three-province, retrospective study found that the overall HepB-BD vaccination rate among all premature infants was 71.41%, which is less than the WHO and China targets of 90%. We found that only 69.57% of premature infants born to mothers with unknown HBsAg status received HepB-BD, in contrast to 93.21% of premature infants born to HBsAg positive mothers, and lower than the target of National Health Commission’s Action Plan for the Elimination of Mother to Child Transmission of AIDS, Syphilis, and Hepatitis B (2022–2025) [11]. Because some mothers with unknown HBsAg status will be HBsAg positive, our findings suggest that there is a significant risk of mother-to-child transmission among premature infants in China, underscoring the importance of universal screening during pregnancy and universal administration of the HepB-BD.

The China Action Plan for Eliminating Mother to Child Transmission of AIDS, Syphilis and Hepatitis B (2022–2025) requires that the screening rate for hepatitis B in pregnant women is 95% or more [11]. Monitoring data show that the HBsAg screening rate of pregnant women has been stable at 99% from 2015 through 2020 [14], but in our study of prematurely born infants, we found that the HBsAg screening rate during pregnancy was lower (91.49%). Although this may be related to a failure to enter data into the hospital information system in time, the lower rate suggests that the screening of pregnant women needs to be improved in some areas. To achieve the WHO goal of eliminating the threat of viral hepatitis by 2030, we also must improve the HepB-BD vaccination rate of all children born to pregnant women infected with hepatitis B virus.

The first dose of hepatitis B vaccine should be administered shortly after birth—the earlier the vaccination, the better will be the protective effect of the vaccine [15]. In 2020, full-series HepB coverage among children 1–4 years old in China was 94.94% [12], and that full-series coverage rate among preterm infants weighing less than 2000 g at birth was 76.92%—less than the China targets of 95%. Birth weight may be related to the relative immaturity of the gastrointestinal tracts of low-birth-weight infants, leading to slower growth and development and lower body weight at birth [16], thus making the infants appear weaker and more susceptible to disease, negatively influencing the timeliness of follow-up HepB doses recommended for the first year of life. Regular physical examinations of children's health and increased education on proper feeding for premature infants may be important methods to increase the weight of premature infants.

HepB-BD coverage among premature infants in Gansu province was higher than in Fujian and Shaanxi provinces—exceeding 90%. However, our sample sizes in Fujian and Henan provinces were much larger than in Gansu (1143 and 448 vs 32), which makes the comparison with Gansu less robust. A study by Fan Li and colleagues in Wuwei City of Gansu Province found that only 31% of premature babies receive a timely birth dose [17]. Li-fang Huang and colleagues studied areas in Fujian during 2017–2019 and found that the HepB-BD vaccination rate in premature infants was 86% [18], significantly higher than the findings in Li and colleagues’ study. Variation in HepB-BD coverage shows the need for local evaluation of program performance.

In accordance with the principle of "whoever delivers the baby vaccinates the baby," the first dose of HepB is administered in the birthing center or hospital, and the follow-up doses are given by vaccination clinics in the jurisdiction. We found that the HepB-BD vaccination rate in premature infants born in hospitals at or above the county level was higher than in hospitals below the county level. Some studies showed that the reasons for delaying vaccination in preterm and low birth weight infants may stem from inappropriate knowledge and misperceptions of parents and health-care providers, who may be uncertain of the safety and efficacy of timely routine childhood vaccinations [19, 20]. The difference by hospital level could be because doctors in hospitals above the county level may have higher educational attainment, medical training opportunities, knowledge, and experience than doctors in hospitals below the county level, possibly leading to confusion or uncertainty about contraindications and precautions to vaccination. Although familiarity with HepB1 vaccination practices may be higher in county and above hospitals, the HepB-BD vaccination rate in preterm infants weighing more than 2000 g was only 75.53%, suggesting interpretation of precautions for preterm infant vaccination in hospitals above the county level was not optimal, and potentially revealing a lack of knowledge of hepatitis B vaccination contraindications [13]. However, this was not evident in our logistic regression analysis and may be an artifact of sample size. Further study is warranted.

Of note, although there was no difference by study year in the HepB-BD for premature babies, the full HepB vaccination rate was higher in 2020 and 2021. In 2020, some vaccination clinic services were suspended during the process of SARS-CoV-2 containment in the early stages of the COVID-19 pandemic. Three vaccinations were excluded from the suspension: HepB-BD, BCG vaccine birth dose, and rabies post-exposure prophylaxis vaccination. After the April 2020 containment, routine vaccinations were caught up throughout China. Fujian, Henan, and Gansu provinces traced and recalled all children who were not fully vaccinated to ensure good coverage of routine program vaccines. Tracing included active search through the real-time dynamic vaccination database and examination of vaccination certificates for children entering kindergartens and schools. A study showed that these measures not only made up for the missed vaccinations due to the suspension of vaccination clinics, but also led to an increase in the number program vaccines received by children in Zhongshan City in 2020 compared to 2017–2019 [21]. The COVID-19 epidemic made people realize the great harm caused by infectious diseases and improved willingness to receive routine vaccinations [22].

China is endemic for hepatitis B. A systematic review and meta-analysis of the HBsAg carrier rate for the general population of China in studies published between 2013 and 2017 showed a seroprevalence of 6.89% [23]. In our three study provinces of Fujian, Henan and Gansu provinces, HBsAg carrier rates were 8.6%, 3.85% and 7.20%, respectively [24–26]. Thus, vertical transmission during childbirth continues to be the main cause of infant HBV infections. Our study found that HepB-BD vaccination of premature infants born to HBsAg positive mothers was higher than the rate in premature infants born to HBsAg negative mothers. This is different than findings of Li-fang Huang, Fan Li, and colleagues, who found a low HepB-BD vaccination rate in premature infants born to HBsAg positive mothers. Our study findings may be related to China's efforts over the years to prevent mother-to-child HBV transmission and to promote hepatitis B education. In 2015, China implemented a nationwide program for prevention of mother-to-child transmission of HIV, syphilis, and hepatitis B. The Guideline for Prevention and Treatment of Viral Hepatitis in China (2017–2020) [10] proposes that the awareness rate of hepatitis among the population should be more than 50% and should be achieved by publicity and education. “National Children's Vaccination Awareness Day” and " World Hepatitis Day" are used to conduct publicity and educational campaigns. Most vaccination clinics hold mother classes that cover vaccination knowledge. Evidence shows that parents who participate in mother classes have significantly higher awareness of vaccination knowledge than parents in non-participating control groups [27, 28].

Our study has limitations. First, subjects were identified from the provincial immunization program information and maternal and child systems. Information such as gestational age, birth weight, and maternal HBsAg came from birth hospitals and was imported into the information system when children were vaccinated at the immunization clinic. Because these information items were not required prior to vaccination, there may have been error or bias in hospital data entry that could affect generalizability to premature infants in the study setting. The HepB-BD vaccination rates in Fujian and Henan provinces were lower than those in Gansu province, and the reasons for the lower timely vaccination rates among mothers with unknown HBsAg status could not be determined based on available variables in the IIS. Further study is warranted. Second, according to the inclusion and exclusion criteria, data exported from the IIS were for children who had received the full 3-dose HepB series, and 5.8% of potential subjects were excluded due to incomplete data. The records of excluded children may have been incomplete either because they had not received the full vaccination series or were vaccinated in a different province. The impact on our study is modest. Third, the immunization information systems could not provide the number of hepatitis B vaccine doses received by all children, precluding our ability to determine the vaccination status of infants under 2000 g who are recommended to receive four doses of hepatitis B vaccine and were born to HBsAg positive women or women with unknown HBsAg status.

Conclusions

HepB-BD coverage among premature infants born during 2019–2021 was 71.41%, which is short of the target of 90%. Premature infants of mothers with unknown HBsAg status had lower HepB-BD coverage and were therefore at risk of mother-to-child transmission of hepatitis B virus. Screening rates for HBsAg should be increased among pregnant women and emphasis should be placed on strengthening doctors' knowledge of vaccination, improving doctors' grasp of hepatitis B vaccine contraindications and precautions, and increasing the rate of timely administration of the first dose of hepatitis B vaccine in preterm infants. We should strengthen families’ infant nutrition knowledge through education, and closely follow premature infants with physical examinations to help them stay healthy, gain body weight, and improve their full-series HepB coverage.

Abbreviations

WHO World Health Organization

IIS Immunization information system

HepB Hepatitis B vaccine

HepB-BD Hepatitis B birth dose, HepB administered within 24 h of birth

HepB1 First HepB dose, the first vaccination after birth

HepB2 Second HepB dose, as per the recommended schedule

HepB3 Third HepB dose, as per the recommended schedule

Acknowledgements

The authors are grateful for the assistance and cooperation of the local field investigators and the surveyed subjects, and the authors thank Lance Rodewald of China CDC for English language editing.

Authors’ contributions

Conceptualization, Fu-zhen Wang; methodology, Li-fang Huang and Ao-di Huang; software, Ao-di Huang and Li-fang Huang; validation, Fu-zhen Wang, Hui Zheng and Zun-dong Yin; formal analysis, Lin Tang; investigation, Li-fang Huang , Jing An and Jun Li; resources, Fu-zhen Wang and Li-fang Huang; data curation, Li-fang Huang; writing—original draft preparation, Li-fang Huang, and Ao-di Huang; writing—review and editing, Fu-zhen Wang, Hui Zheng and Zun-dong Yin; visualization, Fu-zhen Wang; supervision, Lin Tang; project administration, Fu-zhen Wang; funding acquisition, Fu-zhen Wang and Li-fang Huang. All authors have read and agreed to the published version of the manuscript.

Funding

This study was supported by Operation of Public Health Emergency Response Mechanism of China CDC (ID 102393220020010000017), Post vaccination serial test project for children born to mothers with positive hepatitis B virus surface antigen (06245), Young and Middle-aged Backbone Personnel Training Project of Health Science and Technology Program in Fujian Province (2020GGB020), and China Hepatitis Prevention and Control Foundation China Hepatitis B Prevention and Control Research Foundation(YGFK20210077).

Availability of data and materials

The datasets used in the present study are available from the corresponding author (wangfz@chinacdc.cn) on reasonable request.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

The study was approved by the Institutional Review Board of the China CDC (201701) and was conducted according to the guidelines of the Declaration of Helsinki.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Li-fang Huang and Ao-di Huang contributed equally to this study and are co-first authors.
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