Background: The ChAdOx1 nCoV-19 vaccine has been widely administered against SARS-CoV-2 infection; however, data regarding its immunogenicity, reactogenicity, and potential differences in responses among Asian populations remain scarce. Methods: 270 participants without prior COVID-19 were enrolled to receive ChAdOx1 nCoV-19 vaccination with a prime–boost interval of 8–9 weeks. Their specific SARS-CoV-2 antibodies, neutralizing antibody titers (NT50), platelet counts, and D-dimer levels were analyzed before and after vaccination. Results: The seroconversion rates of anti-RBD and anti-spike IgG at day 28 after a boost vaccination (BD28) were 100% and 95.19%, respectively. Anti-RBD and anti-spike IgG levels were highly correlated (r = 0.7891), which were 172.9 ± 170.4 and 179.3 ± 76.88 BAU/mL at BD28, respectively. The geometric mean concentrations (GMCs) of NT50 for all participants increased to 132.9 IU/mL (95% CI 120.0–147.1) at BD28 and were highly correlated with anti-RBD and anti-spike IgG levels (r = 0.8248 and 0.7474, respectively). Body weight index was statistically significantly associated with anti-RBD IgG levels (p = 0.035), while female recipients had higher anti-spike IgG levels (p = 0.038). The GMCs of NT50 declined with age (p = 0.0163) and were significantly different across age groups (159.7 IU/mL for 20–29 years, 99.4 IU/mL for ≥50 years, p = 0.0026). Injection-site pain, fever, and fatigue were the major reactogenicity, which were more pronounced after prime vaccination and in younger participants (<50 years). Platelet counts decreased and D-dimer levels increased after vaccination but were not clinically relevant. No serious adverse events or deaths were observed. Conclusion: The vaccine is well-tolerated and elicited robust humoral immunity against SARS-CoV-2 after standard prime–boost vaccination in Taiwanese recipients.

Background: Fathers’ confidence in supporting their partners’ breastfeeding is crucial for successful breastfeeding outcomes. The paternal version of the Breastfeeding Self-Efficacy Scale-Short Form (BSES-SF) is a globally recognised tool for measuring fathers’ perceived confidence in supporting their partners’ breastfeeding. However, this scale has yet to be validated in Taiwan. This study aimed to evaluate the reliability and validity of the paternal BSES-SF among Taiwanese fathers. Methods: A cross-sectional study was conducted at a baby-friendly hospital in northern Taiwan. Internal consistency and test–retest reliability were examined. Construct validity was evaluated using confirmatory factor analysis and correlations with depressive and anxiety symptoms. Known-groups comparisons were also conducted. Results: A total of 198 fathers completed the study during their partners’ postpartum hospitalisation; of these 76 completed the two weeks retest. The initial one-factor model demonstrated suboptimal fit; after theoretically justified residual covariances were specified, the modified one-factor model achieved acceptable model fit (χ2/df = 2.95; RMR = 0.045; CFI = 0.93; TLI = 0.91; AIC = 278.63). Excellent internal consistency (Cronbach’s alpha = 0.95, 95% confidence interval, CI = 0.94–0.96) and moderate test–retest reliability (intraclass correlation coefficient, ICC = 0.70, 95% CI = 0.53–0.81) were observed. Fathers’ breastfeeding self-efficacy exhibited a significant negative correlation with anxiety ( r = -0.24, p < 0.001) and depressive ( r = -0.18, p = 0.013) symptoms. Evidence of known-groups validity was observed, with significantly higher paternal BSES-SF scores among fathers with two or more children ( p = 0.007) and those whose partners exclusively breastfed ( p < 0.001). Additionally, scores were significantly lower among fathers with education above college level ( p = 0.009) and those with a monthly income above NTD 100,000 ( p = 0.010). After adjustment, higher monthly income remained associated with lower scores, whereas having two or more children and having a partner who exclusively breastfed were associated with higher scores. Conclusion: The paternal BSES-SF demonstrates acceptable psychometric properties for assessing breastfeeding self-efficacy among fathers during the early postpartum period in Taiwan. Healthcare professionals can use this validated tool for timely screening and to offer tailored programs that enhance fathers’ support for sustained breastfeeding.