[Sero-epidemiological study and infection rate evaluation of pertussis in Henan Province].

Objective: To analyze the epidemiological distribution characteristics, influencing factors, and infection rates of pertussis in the population of Henan Province. Methods: From 2022 to 2023, a cross-sectional survey was conducted to investigate the permanent population in Henan Province. Enzyme-linked immunosorbent assay (ELISA) was used to detect anti-pertussis toxin IgG (PT-IgG), analyze the antibody positivity rate (≥20 IU/ml) and median concentration (MC), and estimate the pertussis infection rate based on PT IgG ≥40 IU/ml. The rank sum test was used to compare antibody levels among groups, and the χ2 test was used to compare antibody positive rates and infection rates among groups. Results: A total of 4 810 research subjects were included in this study. The overall positive rate of PT-IgG was 12.10% and MC was 3.04 (0.35, 10.36) IU/ml. There were significant differences both in positive rates and antibody levels of PT-IgG among different regions or age groups (region positive rate: χ2=134.06, P<0.001, MC: H=337.74, P<0.001; age group positive rate: χ2=45.27, P<0.001, MC: H=134.49, P<0.001). Both the positive rate of PT-IgG (25.26%) and MC (8.01 IU/ml) were the highest within one year after completing a full course of vaccination. There were significant differences in positive rates and antibody levels among people receiving different types of pertussis vaccines (positive rate: χ2=12.38, P=0.006, MC: H=17.93, P<0.001). The antibody positivity rate (35.71%) and MC (8.88 IU/ml) of the people who received cell-free pertussis inactivated poliomyelitis influenza type b (combined) vaccine throughout the course were higher than those who received other types of vaccines. The natural infection rate of pertussis was evaluated for individuals aged≥3 years who had no history of pertussis vaccine immunization within the year prior to sampling. With a high vaccination rate, the estimated infection rate of pertussis in the population was 5 757.22/100 000. The infection rates in the 3-year-old (1 940.16/100 000) and 4-year-old (1 765.68/100 000) populations were at a low level among the entire population, reaching their peak at the age of 6 (12 656.71/100 000). Subsequently, although the infection rate continued to decline, it remained at a high level and peaked again at the age of 40-49 years (8 740.39/100 000). There was a statistically significant difference in the estimated infection rate of pertussis among different age groups (χ2=53.21, P<0.001). Conclusion: The PT-IgG level of pertussis in the population of Henan Province is generally at a low level. The estimated infection rate of pertussis is much higher than the reported incidence rate. A booster dose of pertussis vaccine is recommended at 6 years old.

[Seroepidemiological analysis of hepatitis B virus infection among adolescents aged 0-14 years in Henan Province and preliminary evaluation of the effectiveness of childhood hepatitis B vaccine immunization program].

Objective: To analyze the seroepidemiological characteristics of hepatitis B virus (HBV) infection among adolescents aged 0-14 years in Henan Province and to evaluate the effectiveness of the childhood hepatitis B vaccine (HepB) immunization program. Methods: From September 2021 to March 2022, a total of 4 883 adolescents aged 0-14 years were selected from 25 villages or communities of 18 provincial-level cities in Henan Province by using the multi-stage random cluster sampling method. Demographic data were collected through questionnaires. The 3 ml of blood samples were collected from individuals aged 0-4 years and 5 ml of blood samples were collected from individuals aged 5-14 years to test HBsAg, HBcAb and HBsAb. Data on vaccination were collected through Henan Provincial Immunization Information System and hepatitis B cases in Henan Province were collected through China Infectious Disease Reporting System. The effectiveness of the childhood HepB immunization program was analyzed. Results: The average age of 4 883 subjects was (7.32±2.81) years old. The positive rates of HBsAg and HBcAb were 0.1% (7/4 883) and 1.0% (50/4 883), and the population standardized rates were 0.3% and 1.7%. In 2002, the positive rate of HBsAg among adolescents aged 0-14 years in Henan Province was 3.39%. Compared with that in 2002, the number of chronic HBV infections among adolescents in Henan Province in 2022 decreased by about 0.7 million. In 2002, the vaccination rate of newborns who completed all three doses of vaccine was 6.26%. In 2003, the vaccination rate of the hepatitis B vaccine rose rapidly, reaching 90% in 2013 for the first time. After 2014, the vaccination rate in Henan Province continued to remain above 95%. The proportion of cases among children aged 1-4 years in clinical reports decreased from 0.43% (1 108/256 566) in 2006 to 0.01% (78/80 655) in 2021. The proportion of cases among adolescents aged 5-19 years decreased from 18.21% (46 710/256 566) in 2006 to 1.1% (827/80 655) in 2021. Conclusions: From 2002 to 2022, the positive rate of HBsAg among adolescents aged 0-14 years has decreased significantly in Henan Province. The effectiveness of the HepB immunization program for children is good.

[Analysis on the sequence mutation and evolution of HBV genome in China].

Objective: To understand immune escape mutation, drug resistance mutation, and genome evolution information of HBV genome sequence in China. Methods: The whole genome sequence information of HBV in China submitted in GenBank from 1998 to 2021 was selected as the object for analysis. MAFFT method was used for cluster analysis. Analysis of immune escape and drug-resistant mutations was performed using the online tool Gen2pheno. The BEAST 1.10.4 was used for analysis the time evolution of HBV sequences. Results: A total of 5 426 sequences were included in the dataset and distributed in 19 provinces of China. Type C accounted for the highest proportion (59.1%, 3 211/5 426), followed by type B (33.7%, 1 833/5 426). Immune escape mutations were found in 764 sequences (14.1%, 764/5 426). At least one reverse transcriptase region mutation occurred in 98.1% of the sequences. The evolutionary roots of most HBV sequences in China date from around 1801 AD. Conclusion: HBV-resistant mutation rate is high in China. HBV genomes evolve slowly.