Background: Mixing vaccines was proposed as a solution to tackle supply chain interruptions during the crisis of the COVID-19 pandemic. This study aimed to investigate the safety of mixing COVID-19 vaccines for a booster dose in Hanoi, Vietnam. Method: A cross-sectional study was conducted via a telephone-based interview to identify the adverse events following COVID-19 vaccination among 719 participants in Hanoi, Vietnam. Results: In total, 45.76% of participants experienced at least one adverse event following two doses of the COVID-19 vaccine. Most of the adverse events were local effects with mild symptoms such as fever, headache, muscle pain, and/or pain at the site. In general, matching two doses in the same vaccines was not associated with the adverse events as compared to mixing vaccines (OR = 1.43, 96%CI: 0.93–2.2), except matching two doses of Pfizer (OR = 2.25, 95%CI: 1.33–3.82). Conclusion: The findings of this study suggest the overall safety of mixed vaccination. In light of the vaccine shortage, mixing vaccinations for COVID-19 prevention is a good solution. Further studies with larger cohorts and investigating immunity following mixing vaccines are needed to elucidate the mechanism.

Heavy metals (lead [Pb], cadmium [Cd], arsenic [As], mercury [Hg], manganese [Mn], copper [Cu], zinc [Zn], and iron [Fe]) might be risk factors for pre-eclampsia (PE), whereas their joint effect remains unclear. To address this issue, we conducted a nested case–control study consisting of 49 PE cases and 329 controls from a Chinese prospective birth cohort and divided the participants into low/high and quartile groups based on hair metal concentrations. We used logistic regression models and a weighted quantile sum (WQS) model to investigate the independent and mixed associations between these eight heavy metals in maternal hair and the risk of PE. After multivariable adjustment, high hair Pb was associated with a 2.53-fold increased risk of PE, and significantly higher risks of PE were also observed in quartiles 2 to 4 of Pb and quartiles 3 to 4 of Fe. The WQS model revealed a statistically significant association between maternal co-exposure to all eight heavy metals and the risk of PE, with Pb, As, and Fe presenting the biggest risk. Therefore, high maternal exposure to heavy metals may increase the risk of PE. It is crucial to consider co-exposure to multiple heavy metals throughout pregnancy in future research endeavors.

Objectives To describe the SARC-F score distribution and examine factors associated with SARC-F-positive status among community-dwelling older adults recruited from two urban wards in Da Nang, Vietnam. Methods This community-based cross-sectional survey was conducted from March to June 2025. Adults aged 60 years or older were recruited by convenience sampling within proportionally allocated ward targets. SARC-F-positive status was defined as a score of 4 or higher. Modified Poisson regression with robust variance was used to estimate adjusted prevalence ratios (aPRs), with sensitivity analyses for alternative SARC-F cutoffs and continuous age. Results Among 383 participants, mean age was 69.9 years and 57.2% were women. Ninety participants (23.5%; model-based 95% CI, 19.5%-28.0%) were SARC-F-positive. Scores were markedly concentrated immediately below the cutoff: 269 participants (70.2%) scored 3 and none scored 0. Compared with ages 60-70 years, aPRs were 3.34 (95% CI, 2.09-5.34) for ages 71-80 years and 5.11 (95% CI, 3.19-8.18) for ages over 80 years. Any self-reported chronic disease was associated with SARC-F-positive status (aPR, 3.30; 95% CI, 1.85-5.90). Physical-activity estimates were imprecise and attenuated at the higher SARC-F cutoff. Conclusions Older age and self-reported chronic disease were consistently associated with SARC-F-positive status in this recruited sample. The pronounced concentration of scores at 3 and the threshold sensitivity of physical-activity estimates warrant cautious interpretation of cutoff-based results. The 23.5% proportion should not be interpreted as population prevalence or confirmed sarcopenia.