Determining the characteristics of hepatitis B virus (HBV) infection in the healthy population and evaluating the effectiveness of detection strategies will facilitate the optimization of hepatitis B screening strategies in the community and accelerate the elimination of HBV infection in China by the end of 2030. Hepatitis B surface antigen (HBsAg)-electrochemiluminescence immunoassays (ECLIAs), HBsAg-rapid diagnostic tests (RDTs), and HBV DNA-nucleic acid tests (NATs) were performed on serum samples from 2721 community-based healthy participants in Guangdong Province. The screening performance of the RDT and NAT and the distribution characteristics of HBsAg and HBV DNA were evaluated. The prevalence rates of HBsAg-ECLIA, HBsAg-RDT and HBV DNA-NAT in Guangdong Province were 6.10% (95% CI: 5.26~7.06), 4.96% (95% CI: 4.21~5.84) and 6.55% (95% CI: 5.64~7.49), respectively, and the prevalence rates for the three methods for individuals aged over 30 years were 11.18%, 10.92% and 12.57%, respectively. When the ECLIA was used as the gold standard, the sensitivities of the RDT, NAT and RDT and NAT in parallel were 80.7% (95% CI: 73.9~86.4), 86.7% (95% CI: 80.6~91.5) and 93.4% (95% CI: 88.5~96.6), respectively, and the sensitivity of the RDT and NAT in parallel was greater than that of the RDT alone (p < 0.001). The parallel RDT and NAT revealed an additional cost–benefit ratio (ACBR) < 1 for males and individuals aged over 30 years, which indicated that switching from the RDT screening strategy to the RDT and NAT in parallel is more cost effective. Adults aged over 30 years are the main population with hepatitis B infection in Guangdong Province, China, whose prevalence of HBsAg-ECLIA was 11.18%. Single RDT screening is prone to miss individuals with low levels of HBsAg. It is recommended to implement an RDT and NAT in parallel for individuals older than 30 years.

Background Serological surveillance of rubella antibodies is favorable for disease risk assessment and evaluation of vaccination effectiveness, and understanding the immunity status of healthy individuals. Methods From 2021 to 2023, serum samples were collected from healthy residents in Guangzhou and Heyuan of Guangdong Province, China. Rubella IgG antibody levels were determined by enzyme-linked immunosorbent assay (ELISA) and analyzed in combination with vaccination history. Results In this study, a total of 5,092 participants were enrolled, and the positivity rate of rubella IgG antibodies is 84.58% (95% CI: 83.56%-85.56%). The geometric mean concentration (GMC) was 37.45 IU/mL (95% CI: 36.34–38.57). The seropositivity rate and concentration of rubella antibody exhibited a U-shaped curve across age groups. The highest rates were observed in the 8 months − 3 years group (98.21%) and the > 60 years group (92.57%), while the lowest seropositivity rate was found in the 17–25 years group (67.17%). The seropositivity rate in the 2 doses vaccinated group (93.78%) was significantly higher than both the unvaccinated group (82.50%) and the 1 dose vaccinated group (78.67%). Based on the Generalized Additive Model (GAM) prediction, the antibody of 2 doses vaccination group showed an annual decline rate of 5.6%, with predicted persistence for 32.6 years. Conclusions The rubella IgG antibody among healthy populations in Guangdong Province during 2021–2023 remained at a high level. The 2 doses Measles-mumps-rubella combined vaccine (MMR) vaccination could stimulate long-lasting antibody protection. However, lower antibody levels in populations born before China’s NIP implementation, particularly among 17–40 years, suggest an booster vaccination.

BACKGROUND:China implemented diverse varicella vaccination strategies from 2012 to 2022, with unclear protective effects. The study aimed to evaluate the effects of two varicella vaccination (VarV) (the two-dose self-paid VarV and the two-dose free VarV) strategies implemented in Guangdong Province, China. RESEARCH DESIGN AND METHODS:We collected data on varicella cases and doses administered to children aged 0-14 in Guangzhou, Shenzhen, and Foshan from 2012 to 2022. Using Bayesian Structured Time Series (BSTS) model, we estimated the effects of the two VarV strategies in Guangzhou and Shenzhen starting from 2018, by referencing Foshan. RESULTS:Post-implementation of the two-dose self-paid VarV strategy 36,749 (95% CI: 29070, 44428) and 24,179 (95% CI: 16400, 31958) varicella cases were averted in Guangzhou and Shenzhen, with a protection rate of 41.8% (95% CI: 36.3%, 46.5%) and 38.9% (95% CI: 30.2%, 45.7%), respectively. After the adoption of the two-dose free VarV strategy, a substantial relative protection rate of 64.2% (95% CI: 58.0%, 68.7%) in varicella cases was observed in Shenzhen, with 38,828 (95% CI: 29979, 47677) cases averted by 2022. CONCLUSIONS:The two-dose VarV strategies have proven highly effective in reducing varicella incidence. The experience in Shenzhen underscores the benefits of a two-dose free VarV strategy.

The detection of type 3 vaccine-derived poliovirus (VDPV3) in an immunocompetent infant with hand, foot, and mouth disease (HFMD) raised concerns about potential transmission. This study aimed to investigate the risk of VDPV3 spread through comprehensive clinical, environmental, and epidemiological assessments. Existing literature highlights the rare emergence of VDPV3 in similar settings, emphasizing the need for robust surveillance and rapid response to prevent outbreaks. Stool specimen from an 8-month-old female infant presented with HFMD without paralysis or immunodeficiency was tested positive for VDPV3 with 12 nucleotide changes in Foshan City. The infant had received routine vaccinations before and was otherwise healthy. No additional VDPV3 was detected in her follow-up samples, and the child fully recovered without complications. A team was formed to investigate and respond in accordance with China’s National Health Commission and World Health Organization guidelines. Investigation included obtaining stool specimens from the child, her contacts, and local healthy children to test for evidence of poliovirus; conducting enhanced environmental surveillance for VDPV3 in wastewater; measuring vaccination coverage; searching hospitals and communities for unreported acute flaccid paralysis (AFP) cases; and evaluating the index infant for immunodeficiency. No additional VDPV3s were detected in stool samples from the index infant, her contacts, or local healthy children. Similarly, no VDPV3s were identified in wastewater samples. The child’s immune function was found to be normal. Historical vaccination coverage data revealed that Foshan had a high polio vaccination rate. An active search for AFP cases yielded no results. Over a period of more than one year, enhanced AFP surveillance and environmental surveillance were implemented, and no additional VDPV3s were detected during this time. Based on Foshan’s high polio vaccine coverage rate, sensitive AFP case reporting system, and findings from the investigation, risk of transmission of VDPVs in the area was determined to be extremely low. No vaccination response was conducted. After one year of environmental and AFP surveillance, no further VDPV3s were detected, indicating cessation of transmission.

Objective:The objective of our study was to evaluate the vaccine effectiveness (VE) of the pentavalent rotavirus vaccine (RV5) among < 5-year-old children in three provinces of China during 2020-2024 via a propensity score-matched test-negative case-control study. Methods:Electronic health records and immunization information systems were used to obtain data on acute gastroenteritis (AGE) cases tested for rotavirus (RV) infection. RV-positive cases were propensity score matched with RV-negative controls for age, visit month, and province. Results:The study included 27,472 children with AGE aged 8 weeks to 4 years at the time of AGE diagnosis; 7.98% (2,192) were RV-positive. The VE (95% confidence interval, CI) of 1-2 and 3 doses of RV5 against any medically attended RV infection (inpatient or outpatient) was 57.6% (39.8%, 70.2%) and 67.2% (60.3%, 72.9%), respectively. Among children who received the 3rd dose before turning 5 months of age, 3-dose VE decreased from 70.4% (53.9%, 81.1%) (< 5 months since the 3rd dose) to 63.0% (49.1%, 73.0%) (≥ 1 year since the 3rd dose). The three-dose VE rate was 69.4% (41.3%, 84.0%) for RVGE hospitalization and 57.5% (38.9%, 70.5%) for outpatient-only medically attended RVGE. Conclusion:Three-dose RV5 VE against rotavirus gastroenteritis (RVGE) in children aged < 5 years was higher than 1-2-dose VE. Three-dose VE decreased with time since the 3rd dose in children who received the 3rd dose before turning five months of age, but remained above 60% for at least one year. VE was higher for RVGE hospitalizations than for medically attended outpatient visits.

Background. Our study aimed to evaluate vaccine effectiveness (VE) of a live oral pentavalent rotavirus vaccine (RotaTeq, RV5) among < 5-year-old children in three provinces of China via a propensity score matched test negative design case-control study. Methods. We used electronic health records and person-matched immunization information system data to obtain information on acute gastroenteritis (AGE) cases in Guangdong, Beijing, and Hubei provinces evaluated for AGE in emergency department settings and tested for rotavirus (RV) infection during 2020–2024. RV positive cases were propensity-score matched with RV negative subjects on age, visit month, and province. Primary outcomes were medically-attended RVGE infection (inpatient or outpatient), outpatient-only medically-attended RVGE, and RVGE hospitalization. VE was estimated with logistic regression as (1-OR)×100%. Results. The study included 27 472 children with AGE aged 8 weeks to 4 years at the time of the visit; 7.98% (2 192) were rotavirus positive. After propensity score matching of 2 controls for each case, VE (95% confidence interval, CI) of 1–2 and 3 doses of RV5 against infection were 57.6% (39.8%, 70.2%) and 67.2% (60.3%, 72.9%), respectively. Among children who received a third dose < 5-months-old, 3-dose VE decreased from 70.4% (53.9%, 81.1%) (< 5 months) to 65.4% (49.8%, 76.1%) (5 months - <1 year), and to 63.0% (49.1%, 73.0%) (≥ 1 year). Among children who received a third dose ≥ 5-months-old, 3-dose VE decreased from 69.3% (45.9%, 82.6%) (< 5 months) to 61.7% (44.2%, 73.8%) (≥ 1 year). Three-dose VE was 69.4% (41.3%, 84.0%) against hospitalization and 57.5% (38.9%, 70.5%) against outpatient RVGE. Conclusions. Three doses of RV5 provided highest protection against RVGE among < 5-year-old children. Three-dose VE decreased by time since the third dose in children who received a third dose at < 5-months-olds, and remained > 61% ≥1 year after the third dose. VE was higher against RVGE hospitalization than outpatient RVGE.

The evidence regarding the effectiveness of Lanzhou Lamb Rotavirus Vaccine (LLR) and RotaTeq (RV5) against gastroenteritis (RVGE) caused by emerging genotypes in Chinese children remains limited. We conducted a test-negative case–control study using gastroenteritis surveillance data from four cities (2020–2023) in Guangdong Province, China. Children aged 2 months to 5 years hospitalized with acute gastroenteritis were enrolled. Cases were rotavirus-positive; controls were rotavirus-negative. Vaccine effectiveness (VE) was estimated using multivariable logistic regressions. Among 2650 children, 218 (8.2

Background The incidence of rabies exposure is high and increasing in China, leading to an urgent demand of rabies post-exposure prophylaxis (PEP) clinics for the injured. However, the spatial accessibility and inequality of rabies-exposed patients to rabies PEP clinics is less known in China.Methods Based on rabies exposure data, PEP clinic data, and resident travel origin-destination (OD) matrix data in Guangzhou City, China, we first described the incidence of rabies exposure in Guangzhou from 2020 to 2022. Then, the Gaussian two-step floating catchment area method (2SFCA) was used to analyze the spatial accessibility of rabies-exposed patients to rabies PEP clinics in Guangzhou, and the Gini coefficient and Moran's I statistics were utilized to evaluate the inequality and clustering of accessibility scores.Results From 2020 to 2022, a total of 524,160 cases of rabies exposure were reported in Guangzhou, and the incidence showed a significant increasing trend, with an average annual incidence of 932.0/100,000. Spatial accessibility analysis revealed that the overall spatial accessibility scores for three scenarios (threshold of driving duration [d0] = 30 min, 45 min, and 60 min) were 0.30 (95% CI: 0.07, 0.87), 0.28 (95% CI: 0.11, 0.53) and 0.28 (95% CI: 0.14, 0.44), respectively. Conghua, Huangpu, Zengcheng and Nansha districts had the higher accessibility scores, while Haizhu, Liwan, and Yuexiu districts exhibited lower spatial accessibility scores. The Gini coefficient and Moran's I statistics showed that there were certain inequality and clustering in the accessibility to rabies PEP clinics in Guangzhou.Conclusions This study clarifies the heterogeneity of spatial accessibility to rabies PEP clinics, and provide valuable insights for resource allocation to achieve the WHO target of zero human dog-mediated rabies deaths by 2030.

Objectives: To investigate the acceptance and factors influencing acceptance of rubella-containing vaccine (RCV) among women of reproductive age in Guangdong, Henan, Hubei, Liaoning, Shanxi, Sichuan and Zhejiang provinces of China. Methods: Using a stratified sampling method, we selected one urban and one rural community health services center in each of two cities in seven provinces. From these centers, we recruited women 15–49 years of age to complete a questionnaire on their willingness to receive RCV and factors influencing willingness. The survey instrument was adapted from the behavioral and social drivers (BeSD) of vaccination survey tool developed by the World Health Organization. Results: Among 1286 participants, 981 (76.3%) were willing to receive RCV. Awareness of rubella ranged from 12.4% to 70.6%. Willingness to receive RCV differed significantly by region, occupation, vaccination history, and awareness. All latent variables of the structural equation model (SEM) were positively correlated with willingness, and all standardized paths were statistically significant (p < 0.001). Thinking and Feeling had direct positive effects on Social Processes (β = 0.789) and Practical Issues (β = 0.542), thereby indirectly affecting motivation. Conclusions: Women of reproductive age had high willingness to receive the rubella vaccination, but their general awareness of rubella was relatively low. It is necessary to strengthen the health education of women of reproductive age regarding rubella to improve RCV coverage.

Real-world evidence on inactivated COVID-19 vaccines against the highly transmissible B.1.617.2 (Delta) variant of SARS-CoV-2 is limited, leaving an important gap in the evidence base about inactivated COVID-19 vaccines for use by immunization programs.To estimate inactivated vaccine effectiveness (VE) against the B.1.617.2 variant.Retrospective cohort study.The study was based on the first outbreak of the B.1.617.2 variant in mainland China that was discovered and traced in Guangdong in May and June 2021.10 805 adult case patients with laboratory-confirmed infection and close contacts.Participants were categorized as unvaccinated, partially vaccinated (1 dose), and fully vaccinated (2 doses). We estimated VE against the primary outcome of pneumonia and the secondary outcomes of infections, symptomatic infections, and severe or critical illness associated with the B.1.617.2 variant.Results are reported in the order of outcome severity. Of 10 805 participants, 1.3% contracted infections, 1.2% developed symptomatic infections, 1.1% had pneumonia, and 0.2% had severe or critical illness. The adjusted VEs of full vaccination were 51.8% (95% CI, 20.3% to 83.2%) against infection, 60.4% (CI, 31.8% to 88.9%) against symptomatic infection, and 78.4% (CI, 56.9% to 99.9%) against pneumonia. Also, full vaccination was 100% (CI, 98.4% to 100.0%) effective against severe or critical illness. By contrast, the adjusted VEs of partial vaccination against infection, symptomatic infection, and pneumonia were 10.7% (CI, -41.2% to 62.6%), 6.8% (CI, -47.4% to 61.0%), and 11.6% (CI, -42.6% to 65.8%), respectively.Observational study with possible unmeasured confounders; insufficient data to do reliable subgroup analyses by age and vaccine brand.Full vaccination with inactivated vaccines is effective against the B.1.617.2 variant. Effort should be made to ensure full vaccination of target populations.National Natural Science Foundation of China and Key-Area Research and Development Program of Guangdong Province.

Real-world evidence on inactivated COVID-19 vaccines against the SARS-CoV-2 B.1.617.2 (Delta) variant is limited. The authors of this cohort study analyzed vaccination, surveillance, screening, tracing, and quarantine data to determine the effectiveness of inactivated COVID-19 vaccines against infections, pneumonia, and severe or critical illness caused by the Delta variant.

This study aimed to describe the spread of coronavirus disease 2019 (COVID-19) from Wuhan to rural villages in the Hubei Province The analysis revealed the following: 1) COVID-19 spread from Wuhan to other cities and rural areas in Hubei, but the disease did not become widespread in rural villages because of strict prevention measures and urbanization;2) According to the fluctuation in the number of confirmed cases reported in Hubei after January 23, 2020, we inferred that the infected patients on the same day will become ill during the next 20 days;3) the advanced traffic system facilitates the direct spread of COVID-19 from Wuhan to counties, towns, and villages in the Hubei Province There is a low possibility of COVID-19 spread from prefecture-level cities to rural areas The findings imply that the government should limit the travelers from the cities to the rural areas, pay more attention to the prevention and control of SARS-CoV-2 in cities, and appropriately prolong the isolated observation period of travelers

Background. This study aimed to describe the spread of coronavirus disease 2019 (COVID-19) from Wuhan to rural villages in the Hubei Province. Methods. The analysis revealed the following: (1) COVID-19 spread from Wuhan to other cities and rural areas in Hubei, but the disease did not become widespread in rural villages because of strict prevention measures and urbanization; (2) according to the fluctuation in the number of confirmed cases reported in Hubei after January 23, 2020, we inferred that the infected patients on the same day will become ill during the next 20 days; (3) the advanced traffic system facilitates the direct spread of COVID-19 from Wuhan to counties, towns, and villages in the Hubei Province. Results. There is a low possibility of COVID-19 spread from prefecture-level cities to rural areas. Conclusions. The findings imply that the government should limit the travelers from the cities to the rural areas, pay more attention to the prevention and control of severe acute respiratory syndrome coronavirus 2 in cities, and appropriately prolong the isolated observation period of travelers.

Background: HIV-1 CRF55_01B was first reported in 2013. At present, no report is available regarding this new clade’s polymorphisms in its functionally critical regions protease and reverse transcriptase. Objective: To identify the diversity difference in protease and reverse transcriptase between CRF55_01B and its parental clades CRF01_AE and subtype B; and to investigate CRF55_01B’s drug resistance mutations associated with the protease inhibition and reverse transcriptase inhibition. Methods: HIV-1 RNA was extracted from plasma derived from a MSM population. The reverse transcription and nested PCR amplification were performed following our in-house PCR procedure. Genotyping and drug resistant-associated mutations and polymorphisms were identified based on polygenetic analyses and the usage of the HIV Drug Resistance Database, respectively. Results: A total of 9.24 % of the identified CRF55_01B sequences bear the primary drug resistance. CRF55_01B contains polymorphisms I13I/V, G16E and E35D that differ from those in CRF01_AE. Among the 11 polymorphisms in the RT region, seven were statistically different from CRF01_AE’s. Another three polymorphisms, R211K (98.3%), F214L (98.3%), and V245A/E (98.3 %.), were identified in the RT region and they all were statistically different with that of the subtype B. The V179E/D mutation, responsible for 100% potential low-level drug resistance, was found in all CRF55_01B sequences. Lastly, the phylogenetic analyses demonstrated 18 distinct clusters that account for 35% of the samples. Conclusions: CRF55_01B’s pol has different genetic diversity comparing to its counterpart in CRF55_01B’s parental clades. CRF55_01B has a high primary drug resistance presence and the V179E/D mutation may confer more vulnerability to drug resistance.

Coronavirus disease 2019 (COVID-19) is caused by SARS-CoV-2 infection and was first reported in central China in December 2019. Extensive molecular surveillance in Guangdong, China's most populous province, during early 2020 resulted in 1,388 reported RNA-positive cases from 1.6 million tests. In order to understand the molecular epidemiology and genetic diversity of SARS-CoV-2 in China, we generated 53 genomes from infected individuals in Guangdong using a combination of metagenomic sequencing and tiling amplicon approaches. Combined epidemiological and phylogenetic analyses indicate multiple independent introductions to Guangdong, although phylogenetic clustering is uncertain because of low virus genetic variation early in the pandemic. Our results illustrate how the timing, size, and duration of putative local transmission chains were constrained by national travel restrictions and by the province's large-scale intensive surveillance and intervention measures. Despite these successes, COVID-19 surveillance in Guangdong is still required, because the number of cases imported from other countries has increased.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major multidrug-resistant (MDR) opportunistic pathogen that is responsible for nosocomial infections worldwide. The emergence of MRSA in food-producing animals has heightened concerns regarding the presence of MRSA in foods having an animal origin. The objectives of this study were to determine the prevalence of MRSA in different sources, including retail food, food-producing animals, and food handlers in Sichuan province. During 2007-2015, S. aureus was isolated from samples having different origins. Susceptibilities of MRSA to a panel of 12 antimicrobial agents were determined according to Clinical and Laboratory Standards Institute (CSLI) procedures. Pulsed-field gel electrophoresis, spa typing, staphylococcal chromosomal cassette (SCC) mec typing, and multilocus sequence typing (MLST) were used to characterize the relationship between these isolates. A total of 756 S. aureus were isolated from 11,067 samples. Of these, 52 isolates were classified as MRSA based on the presence of mecA genes. An antimicrobial susceptibility assay indicated that CHL-CLI-ERY-FOX-OXA-PEN-TET (n=10) and CHL-CIP-CLI-ERY-FOX-OXA-PEN-TET (n=8) were the two predominant MDR profiles in the isolates. Using 60% genetic similarity as a cutoff, the 52 MRSA isolates were grouped into 6 clusters having 34 pulsotypes. MLST typing showed seven multilocus sequence types (STs) with ST59 and ST9 being the most common. Six SCCmec types were identified in all MRSA isolates. The MRSA isolates had relatively low prevalence in Sichuan province. Clonal expansion is not involved in the dissemination of MRSA from food origins. Considering the threat of MRSA to public health, further surveillance is required to monitor the prevalence of food-related MRSA.

Background: WHO recommends the use of rubella-containing vaccine (RCVs) to prevent rubella and congenital rubella syndrome (CRS). Most licensed rubella vaccines in use globally are based on RA27/3 strains and have estimated vaccine effectiveness (VE) rates of 95-100%. In contrast, China uses a BRD-II strain-based rubella vaccine. Few field studies have been conducted that estimate VE of China's RCV. On March 17, 2014, a rubella outbreak was reported in a middle school in Guangzhou city, China. We conducted an investigation to understand reasons for the outbreak, and we used that investigation to estimate vaccine effectiveness of China's rubella vaccine.Methods: To identify cases, investigators reviewed records kept by the school doctor and absentee records kept by teachers. Self-administered questionnaires were sent to parents of all students to collect information about the students' symptoms, the results of any physician consultation, and disease history. We obtained demographic information and illness information for all students in the school; vaccination status was determined by inspection of official, parent-held vaccination records. A retrospective cohort study was conducted in 13 classes that had secondary cases of rubella. Using the secondary attack rates, we evaluated VE by the number of RCV doses received and age at vaccination.Results: During the period February 17-May 23, 2014, 162 students (50 suspected cases, 88 probable cases, 24 confirmed cases) were diagnosed with rubella, yielding an overall attack rate of 10% (162/1621). Cases occurred in 27 classes (73%) of 37 classrooms. Secondary cases occurred in 13 classes (35%) of 37 classrooms. A total of 1130 students (69.7%) have vaccination certificates; 419(37%) students were record-confirmed to have received RCV. For those vaccinated using BRD-II strain vaccine, vaccine effectiveness (VE) was 94% (95%CI: 75-98). VE for measles, mumps, and rubella (MMR) vaccine which is based on either BRD-II or RA27/3 strain was 89% (95%CI: 56-97). VE of a single dose of domestic monovalent rubella vaccine that used BRD-II strain vaccine was 93% (95%CI: 73-98). VE for those who received the vaccine between 1 and 2 years of age was 95% (95% CI: 67-99) while the VE was 100% for those vaccinated after 2 years of age. VE among those who received RCV <12 years ago was 100% while VE among those who received RCV >= 12 years ago was 92% (95%CI: 70-98).Conclusions: The rubella vaccines used in China that are based on the BRD-II rubella vaccine strain have VE of 94%, which is similar to the more commonly used RA27/3-based RCVs. Low vaccination coverage contributed to this outbreak; early reporting of an outbreak is necessary for effective outbreak response immunization. (C) 2015 Elsevier Ltd. All rights reserved.

OBJECTIVE:To investigate the epidemic status of Hepatitis B in children aged 1-14 in 3 counties of Guangdong province in 2013, and to evaluate the effect of hepatitis control in children aged 1-14 after hepatitis B vaccine was integrated into the national immunization program in 2002 and catch-up vaccination was conducted from 2009 to 2011.METHODS:A multi-stage stratified random sampling was designed to survey 1 621 children aged 1-14 in rural area of Nanxiong county, Haifeng county and Xinxing county by questionnaires including general information, medical history and risk factors. The samples were tested with chemiluminescence method to detect hepatitis B virus (HBV) surface antigen (HBsAg), antibody to HbsAg (anti-HBs) and antibody to HBV core antigen (anti-HBc). Chi-square test was used to compare the positive rate of HBV serum markers in different age groups, vaccine histories, birth weight and HBV infection status of mother.RESULTS:Among the children aged 1-14 in 3 counties rural regions of Guangdong province, the positive rate of HBsAg, anti-HBs, and anti-HBc was 1.11% (18/1 621), 60.69% (982/1 618) and 1.92% (31/1 617), respectively. The HBsAg positive rate of vaccinated children (0.84%, 13/1 547) was lower than that of unvaccinated children (1/13) or children with unknown vaccination status (6.56%, 4/61) (χ² = 22.64, P < 0.001). The HBsAg positive rate (0.45%, 5/1 118) of the children with birth-dose given within 24 hours was lower than those that of children given beyond 24 hours (2.63%, 61/190) (χ² = 10.21, P < 0.001). The HBsAg positive rate (5/18) of children with birth weight under 2 kilogram was higher than that of children with birth weight above 2 kilogram (0.78%, 12/1 548) (χ² = 120.8, P < 0.001). The HBsAg positive rate of children born to HBsAg-positive mothers (2.80%, 3/107) was higher than that of children born to HBsAg-negative mothers (0.21%, 1/470) (χ² = 8.50, P = 0.004). With the age increasing, the coverage and timely birth-dose coverage of Hepatitis B vaccine (HepB) decreased, and the positive rate of anti-HBs gradually decreased.CONCLUSION:After the catch-up vaccination was conducted in unvaccinated children aged 1-14 years from 2009 to 2011, the HBsAg and anti-HBc positive rate decreased, while the anti-HBs positive rate increased significantly.