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Chronic liver disease (CLD) entails elevated risk of COVID-19 severity and mortality. The effectiveness of the booster dose of inactivated SARS-CoV-2 vaccine in stimulating antibody response in CLD patients is unclear. Therefore, we conducted a cross-sectional study involving 237 adult CLD patients and 170 healthy controls (HC) to analyze neutralizing antibodies (NAbs) against SARS-CoV-2 prototype and BA.4/5 variant, anti-receptor binding domain (RBD) IgG, and total anti-SARS-CoV-2 antibodies. Serum levels of the total anti-SARS-CoV-2 antibodies, anti-RBD IgG and inhibition efficacy of NAbs were significantly elevated in CLD patients after the booster dose compared with the pre-booster dose, but were relatively lower than those of HCs. Induced humoral responses decreased over time after booster vaccination. The neutralization efficiency of the serum against BA.4/5 increased but remained below the inhibition threshold. All four SARS-CoV-2 antibodies, including total anti-SARS-CoV-2 antibodies, anti-RBD IgG and NAbs against prototype and BA.4/5, were lower in patients with severe CLD than those with non-severe CLD. After booster shot, age and time after the last vaccine were the risk factors for seropositivity of NAb against BA.4/5 in CLD patients. Additionally, white blood cell counts and hepatitis B core antibodies were the protective factors, and severe liver disease was the risk factor associated with seropositivity of total anti-SARS-CoV-2 antibodies. Overall, our data uncovered that antibody responses were improved in CLD patients and peaked at 120 days after the booster vaccines. All antibodies excepting total anti-SARS-CoV-2 antibodies declined after peak. CLD patients exhibited impaired immunologic responses to vaccination and weakened NAbs against BA.4/5, which hindered the protective effect of the booster shot against Omicron prevalence. Cellular immune responses should be further evaluated to determine the optimal vaccine regimen for CLD patients.

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SARS-CoV-2 vaccination has been recommended for liver transplant (LT) recipients. However, our understanding of inactivated vaccine stimulation of the immune system in regulating humoral and cellular immunity among LT recipients is inadequate. Forty-six LT recipients who received two-dose inactivated vaccines according to the national vaccination schedule were enrolled. The clinical characteristics, antibody responses, single-cell peripheral immune profiling, and plasma cytokine/chemokine/growth factor levels were recorded. Sixteen (34.78%) LT recipients with positive neutralizing antibody (nAb) were present in the Type 1 group. Fourteen and 16 LT recipients with undetected nAb were present in the Type 2 and Type 3 groups, respectively. Time from transplant and lymphocyte count were different among the three groups. The levels of anti-RBD and anti-S1S2 decreased with decreasing neutralizing inhibition rates. Compared to the Type 2 and Type 3 groups, the Type 1 group had an enhanced innate immune response. The proportions of B, DNT, and CD3+CD19+ cells were increased in the Type 1 group, whereas monocytes and CD4+ T cells were decreased. High CD19, high CD8+CD45RA+ cells, and low effector memory CD4+/naïve CD4+ cells of the T-cell populations were present in the Type 1 group. The Type 1 group had higher concentrations of plasma CXCL10, MIP-1 beta, and TNF-alpha. No severe adverse events were reported in all LT recipients. We identified the immune responses induced by inactivated vaccines among LT recipients and provided insights into the identification of immunotypes associated with the responders.

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We estimated the effectiveness of two doses of the ChAdOx1 nCoV-19 (Covishield) vaccine against any COVID-19 infection among individuals ≥45 years in Chennai, Tamil Nadu, India. A community-based cohort study was conducted from May to September 2021 in a selected geographic area in Chennai. The estimated sample size was 10,232. We enrolled 69,435 individuals, of which 21,793 were above 45 years. Two-dose coverage of Covishield in the 18+ and 45+ age group was 18% and 31%, respectively. Genomic analysis of 74 out of the 90 aliquots collected from the 303 COVID-19-positive individuals in the 45+ age group showed delta variants and their sub-lineages. The vaccine's effectiveness against COVID-19 disease in the ≥45 age group was 61.3% (95% CI: 43.6-73.4) at least 2 weeks after receiving the second dose of Covishield. We demonstrated the effectiveness of two doses of the ChAdOx1 vaccine against the delta variant in the general population of Chennai. We recommend similar future studies considering emerging variants and newer vaccines. Two-dose vaccine coverage could be ensured to protect against COVID-19 infection.

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A COVID-19 booster vaccination is being comprehensively evaluated globally due to the emerging concern of reduced protection rate of previous vaccination and circulating Variants of Concern (VOC). But the safety and immunogenicity of homologous BBIBP-CorV boosting vaccination are yet to be thoroughly evaluated. We conducted this prospective, open-label study in Huashan Hospital using a third 6.5U BBIBP-CorV administered at an interval of 4-8 months following the previous two doses in healthy adults. Safety, anti-RBD response and neutralizing titers against SARS-CoV-2 and VOCs were examined. Sixty-three and forty participants entered the booster and the control group, respectively. A significant increase in IFN-γ SFU per million PBMCs was observed on day 14 against N peptide (20 vs. 5, P < 0.001). On day 14, pVNT GMTs increased over 15 folds of the baseline levels against prototype to reach 404.54 titers and over 9-13 folds against 4 VOCs and continuously increased by day 28. sVNT GMTs increased 112.51 and 127.45 folds by days 14 and 28 compared to the baseline level. Median anti-RBD antibody and IgG level significantly increased from 11.12 to 2607.50 BAU/ml and 4.07 to 619.20 BAU/ml on day 14. On day 14, females showed a significantly higher cell-mediated immune response against S1 peptide. The 7-8 months interval group had a higher humoral response than the 4-6 months interval group. No severe adverse event was reported. A third homologous BBIBP-CorV boosting vaccination was safe and highly immunogenic for healthy adults and broadened participants' immunity against VOCs.

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