Prevalence of hepatitis B surface antigen (HBsAg) in a blood donor population born prior to and after implementation of universal HBV vaccination in Shenzhen, China

Abstract

BackgroundNeonatal hepatitis B vaccination program at birth has been implemented nationwide since 1992 in China. However, current HBV prevalence status in blood donors has not been entirely examined, which may impact HBV safety in blood donations as the vaccinees over 18 years old progressively become the majority population of blood donors.MethodsIn this study, 569,145 blood donors were screened for HBsAg by rapid tests and enzyme immunoassays, among them 475,538 blood samples with negative HBsAg were further screened for HBV DNA by nucleic acid testing between 2005 and 2014 at Shenzhen blood center.ResultsAn overall 2.3 % HBsAg prevalence was found in the blood donor population during the past 10 years (2.86 % in 2005, 1.76 % in 2010, and 2.79 % in 2014, respectively). HBsAg seroconversion occurred in 0.37 % of repeat-donors. When stratified by age, the prevalence of HBsAg was found significantly higher in younger donors age 18–25 years (2.73 %) than in those 26–35 years (2.13 %), 36–45 years (2.03 %) and 46–58 years (1.71 %) (P < 0.001), unexpectedly suggesting that younger donors remained at risk of chronic HBV infection. Assuming that donors aged 18–22 born before or after 1992 were non-vaccinated and vaccinated, respectively, HBsAg prevalence was higher in first-time donors born ≥1992 (3.9 %) than prior to 1992 (3.5 %, P = 0.005). The incidence of HBV infection in the 5-year period examined was significantly lower in repeat-donors born ≥1992 (0.27 %) than prior to 1992 (0.6 %, P = 0.008). The yield of HBV DNA+/HBsAg- donors was 1:3,302, including 1:4,486 occult infections and 1:43,231 window period infections.ConclusionYoung blood donors born after implementation of universal HBV vaccination in China presented higher prevalence of HBsAg but lower incidence of HBsAg seroconversion than older, presumed unvaccinated, donors. HBV vaccine boosting for adolescents at 15–17 years old prior to reaching blood donor age might help improve blood safety.

Incidence of hepatitis B virus infection in young Chinese blood donors born after mandatory implementation of neonatal hepatitis B vaccination nationwide

“…Donor GZ9099 had high‐risk behaviour with multiple sexual partners, donor GZ1487 lived with an HBsAg+ roommate, and donor GZ2605's mother was HBsAg+ carrier. Thus, incident HBV infection in young adults might be related to waning of vaccine‐induced anti‐HBs and allow infection by close contact with an HBV carrier rather than developing breakthrough infection as reported previously . Overall, half of young repeat donors with anti‐HBs <100 IU/L may not have sufficient protection against HBV infection when exposed, particularly to high viral load .…”

“…In the same donor population, 1:1494 HBsAg−/HBV DNA+ donors were detected with Ultrio NAT (10.4 IU/mL). Using the higher sensitivity Ultrio Plus NAT (3.4 IU/mL), 1:200 additional HBV DNA+ cases were detected from anti‐HBc+ repeat donors, suggesting that higher sensitivity of NAT would improve HBV safety where HBV prevalence is high . The tendency of HBV DNA to fluctuate at low levels in OBIs is well recognized and might account for 4/9 cases shown in Table missed by the initial, less‐sensitive NAT in the first‐time donation screening, while the others are likely recent HBV infections as suggested by high anti‐HBs levels.…”

“…Thus, incident HBV infection in young adults might be related to waning of vaccine-induced anti-HBs and allow infection by close contact with an HBV carrier rather than developing breakthrough infection as reported previously. 8,15,22 Overall, half of young repeat donors with anti-HBs <100 IU/L may not have sufficient protection against HBV infection when exposed, particularly to high viral load. 15,31,32 Vaccinated individuals might lose anti-HBs reactivity, waning off over time, [33][34][35][36] but might also develop an anamnestic response to HBV when exposed.…”

Estimation of hepatitis B–positive rates in Chinese blood donors by combining predonation and postdonation screening results

“…HBsAg‐positive rates at these two blood centers are much lower than in the general Chinese population, perhaps an expected result considering the effect of donor education, selection, and the nationwide vaccination program since 1992 . In theory, individuals born after 1992 have lower HBV‐positive rate and their participation in blood donation will contribute to continuous decrease of HBV rate in donors especially since about 60% of first‐time and one‐third of repeat donations came from donors 18 to 25 years old . Chongqing’ having a significantly higher proportion of young donors (25 years of age or younger) who had lower confirmatory positive rate than in Mianyang are likely among the contributing factors to its lower HBV‐positive rate.…”

“…2,15 In theory, individuals born after 1992 have lower HBV-positive rate and their participation in blood donation will contribute to continuous decrease of HBV rate in donors especially since about 60% of first-time and one-third of repeat donations came from donors 18 to 25 years old. 16 Chongqing' having a significantly higher proportion of young donors (25 years of age or younger) who had lower confirmatory positive rate than in Mianyang are likely among the contributing factors to its lower HBV-positive rate.…”