Objective: Ursodeoxycholic acid (UDCA) may reduce susceptibility to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection by downregulating angiotensin-converting enzyme 2 (ACE2), based on recent experimental investigation. This study aimed to determine the potential protective effect of UDCA against SARS-CoV-2 infection in patients with chronic liver disease.Methods: Patients with chronic liver disease receiving UDCA (taking UDCA ≥1 month) at Beijing Ditan Hospital between January 2022 and December 2022 were consecutively enrolled. These patients were matched in a 1:1 ratio to those with liver disease not receiving UDCA during the same period by using a propensity score matching analysis with nearest neighbor matching algorithm. We conducted a phone survey of coronavirus disease 2019 (COVID-19) infection during the early phase of the pandemic liberation (from 15 December 2022 to 15 January 2023). The risk of COVID-19 was compared in two matched cohorts of 225 UDCA users and 225 non-UDCA users based on patient self-report.Results: In the adjusted analysis, the control group was superior to the UDCA group in COVID-19 vaccination rates and liver function indicators, including γ-glutamyl transpeptidase and alkaline phosphatase (p < 0.05). UDCA was associated with a lower incidence of SARS-CoV-2 infection (UDCA 85.3% vs. control 94.2%, p = 0.002), more mild cases (80.0% vs. 72.0%, p = 0.047), and shorter median time from infection to recovery (5 vs. 7 days, p < 0.001). Logistic regression analysis showed that UDCA was a significant protective factor against COVID-19 infection (OR: 0.32, 95%CI: 0.16–0.64, p = 0.001). Furthermore, diabetes mellitus (OR: 2.48, 95%CI: 1.11–5.54, p = 0.027) and moderate/severe infection (OR: 8.94, 95%CI: 1.07–74.61, p = 0.043) were more likely to prolong the time from infection to recovery.Conclusion: UDCA therapy may be beneficial in reducing COVID-19 infection risk, alleviating symptoms, and shortening the recovery time in patients with chronic liver disease. However, it should be emphasized that the conclusions were based on patient self-report rather than classical COVID-19 detection by experimental investigations. Further large clinical and experimental studies are needed to validate these findings.

Objectives: Accumulating evidence has confirmed the efficacy and safety of COVID-19 vaccines against SARS-CoV-2 infection. However, the effect of COVID-19 vaccination on immuno-virological parameters in people with HIV (PWH) is uncertain. Methods: A total of 372 PWH treated at Beijing Ditan Hospital were included. Unvaccinated PWH were matched 1:3 with vaccinated PWH using a propensity score matching algorithm. Differences in immuno-virological markers between the matched groups were analyzed. The Wilcoxon signed rank test was used to test for changes in CD4 and CD8 counts and HIV viral load over two months around vaccination. In addition, we investigated the long-term changes in HIV-related markers in different vaccination dose groups and in the entire vaccinated population. Results: Vaccinated PWH had a higher CD4/CD8 ratio (0.64 (0.49, 0.78) vs. 0.80 (0.56, 1.03), p = 0.037) than unvaccinated PWH within a two-month window after the third dose. There were 337 PWH who received COVID-19 vaccination, and 73.9% (n = 249) received three doses of vaccine. We observed a transient increase in CD4 count and CD4/CD8 ratio within a two-month window after vaccination, especially after the second dose (CD4 count: 583.5 (428.5, 706.8) vs. 618.0 (452.0, 744.0), p = 0.018; CD4/CD8 ratio: 0.70 (0.50, 0.91) vs. 0.71 (0.53, 0.96), p < 0.001)) and the third dose (CD4 count: 575.5 (435.5, 717.0) vs. 577.5 (440.8, 754.8), p = 0.001; CD4/CD8 ratio: 0.70 (0.52, 0.93) vs. 0.79 (0.53, 1.00), p < 0.001)). Recent CD4 counts and CD4/CD8 ratios were lower than after COVID-19 but remained higher than before COVID-19 in vaccinated PWH. In addition, COVID-19 vaccination had no negative effect on HIV viral load. Conclusions: A transient increase in CD4 count and CD4/CD8 ratio was observed after COVID-19 vaccination. However, the enhanced cellular immune response induced by vaccination may diminish over time and return to normal levels. There is no adverse effect of vaccination on HIV viral load.

Background and Objectives: The relationship between circulating retinol-binding protein 4 (RBP4) levels and hepatitis C virus (HCV) infection remains unclear. This study aims to systematically assess RBP4 expression in patients with HCV and its correlation with disease severity. Materials and Methods: We searched the Embase, PubMed, and Cochrane databases for relevant studies up to 1 January 2024. This study was registered on PROSPERO (CRD42023489051). Results: Our analysis included eight studies with 2612 participants (1152 controls and 1282 patients with HCV). Overall, RBP4 levels did not significantly differ between patients with HCV and controls (SMD: −0.36; 95% CI: −0.94, 0.23; p = 0.23). However, in a subgroup of Asian subjects, patients with HCV showed significantly lower RBP4 levels (SMD: −0.40; 95% CI: −0.49, −0.31; p = 0.10). Additionally, a negative correlation between RBP4 levels and disease severity was observed across all studied populations. Conclusions: RBP4 levels may vary due to HCV genotype, ethnicity, and environmental factors. In the context of HCV infection, RBP4 levels appear to reflect the severity of disease progression. Our findings indicate that RBP4 could serve as a biomarker for HCV disease progression. Further research is needed to elucidate the complex mechanisms of RBP4 in HCV infection.