Predictors of immune persistence induced by two-dose BBIBP-CorV vaccine in high-risk occupational population.

BACKGROUND: The immune protection from infection may wane over time as neutralizing antibody levels decline. We aimed to develop a nomogram to predict long-term immune persistence induced by two-dose BBIBP-CorV vaccine and calculate the neutralizing antibody decline probability of individuals. METHODS: In the initial study, a total of 809 participants were recruited and randomly allocated (1:1:1) to vaccination group with three two-dose schedules on days 0 and 14, 0 and 21, or 0 and 28. The participants with neutralizing antibody titers of 16 or above on day 28 after the second dose were followed up at month 3, 6 and 10. Multivariable Cox proportional hazards regression model and nomogram model were used to identify predictors associated with maintaining of neutralizing antibody levels during 10 months after the second dose. RESULTS: A total of 744 participants followed up at day 28 after the second dose. The participants with age ≥ 50 (aHR = 3.556, 95 %CI: 1.141-4.884, P = 0.028) were associated with a high risk of response loss (titers < 16). The participants who were in 0-28 d group (aHR = 0.403, 95 %CI: 0.177-0.919, P = 0.031), had an influenza vaccination history (aHR = 0.468, 95 %CI: 0.267-0.921, P = 0.033) or were female (aHR = 0.542, 95 %CI: 0.269-0.935, P = 0.035) tended to maintain immune persistence during 10 months after the second dose. The nomogram was constructed and showed moderate discrimination[C-index:0.711 (95 %CI: 0.652-0.770); AUC: 0.731 (95 %CI: 0.663-0.792)] and good calibration. CONCLUSIONS: From 28 days to 10 months after receipt of the second dose of the BBIBP-CorV vaccine, neutralizing antibody levels were substantially decreased, especially among men, among persons 50 years of age or older, among persons with the 0-14 d group, and among persons without history of influenza vaccination. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2100041705, ChiCTR2100041706.

Decreased placental TLR3 is associated with hepatitis B virus vaccine responsiveness in infants born to HBsAg-positive mothers.

Background: Although hepatitis B vaccination has a significant impact on the reduction hepatitis B virus (HBV) infection, babies born to hepatitis B surface antigen (HBsAg) positive mothers bear a high risk of being poor responsive to the vaccine with unilluminated mechanism. Toll-like receptor 3 (TLR3) plays a vital role in placental immunity, which affects the immune response of these babies. This study investigated the role of placental TLR3 in the immune responses of babies born to HBsAg-positive mothers to the HBV vaccine. Methods: One hundred pairs of HBsAg-positive mothers and their newborns were recruited. Maternal blood samples were collected before delivery, and placental tissues were collected after delivery. Newborns were administered standard passive and active immunoprophylaxis and followed up until the age of 1. Infant blood samples were collected at 1 year of age. Mothers and infants were tested for HBV serological markers and HBV DNA by electrochemiluminescence immunoassay and fluorescence quantitative polymerase chain reaction. respectively. Placental TLR3 was detected by immunohistochemistry and score in a semi-quantitative fashion, circulating cytokines in infants were detected by enzyme-linked immunosorbent assay. Infants with anti-HBs ≥100 and <100 mIU/mL were classified into the high-responsiveness group and the non- or hypo-responsiveness group. Results: The TLR3 protein was expressed in all placentas. Compared with the high-responsiveness group, the expression of TLR3 in the non- or hypo-responsiveness group was significantly decreased (χ2=10.39, P=0.001). A non-conditional logistic regression model showed that the increased expression of placental TLR3 protein decreased the odds of HBV vaccine non- or hypo-responsiveness in the babies of HBsAg-positive mothers [OR =0.25 (95% CI: 0.11-0.58)], and this association remained significant after accounting for maternal factors, such as HBeAg and HBV DNA, as well as infant cytokines, including IL-6, IL-12, TNF-α, IFN-α, and IFN-γ [OR =0.15 (95% CI: 0.05-0.44)]. Conclusions: Decreased placental TLR3 expression is associated with impaired responsiveness to HBV vaccination in babies born to HBsAg-positive mothers.

Immune persistence induced by two-dose BBIBP-CorV vaccine with different intervals, and immunogenicity and safety of a homologous booster dose in high-risk occupational population.

BACKGROUND: The immune persistence of neutralizing antibodies elicited by BBIBP-CorV vaccines on day 0-14, 0-21 and 0-28 schedule, and the immunogenicity and safety of a homologous booster dose after different priming vaccination regimens is scarcely reported. METHODS: : Responders (GMT≥16) at day 28, after priming with the two-dose vaccine, were followed up at 3, 6, and 10 months. Eligible participants received a homologous booster dose at month 10 and were followed-up 28 days post-booster. RESULTS: The GMT of neutralizing antibodies in 0-28d-10 m and 0-21d-10 m group were significantly higher than 0-14d-10 m group from month 3 (71.6 & 64.2 vs 46.4, p < 0.001) to month 10 (32.4 & 28.8 vs 20.3, p < 0.001) after the second dose. On day 28 post-booster, a remarkable rebound in neutralizing antibodies (246.2, 277.5, and 288.6, respectively) was observed in the three groups. All adverse reactions were mild after booster injection. CONCLUSIONS: The priming two-dose BBIBP-CorV vaccine with 0-28 days and 0-21 days schedule could lead to a longer persistence of neutralizing antibody than the 0-14 days schedule. Regardless of the priming vaccination regimens, a homologous booster dose led to a strong rebound in neutralizing antibodies and might persist for at least 18 months.