Objective: To assess the acceptance of coronavirus disease (COVID-19) vaccine among healthcare workers at two general hospitals in Vietnam when it is available. Methods: A cross-sectional study was conducted using a convenience sampling from January to February 2021 among 410 healthcare workers at two general hospitals in Vietnam via a self-administered questionnaire. A multivariable regression analysis was performed to determine predictors of vaccine acceptance including the demographic factors, COVID-19 knowledge, and vaccine beliefs based on the domains of Health Belief Model. Results: Among 410 healthcare workers, 76.10% showed vaccination willingness. Predictors of acceptance were determined that the group reporting as 'vaccine acceptance' was more likely to be positive towards the perceived susceptibility and severity of COVID-19 (OR 2.45; 95% CI 1.48-4.06, P<0.05), perceived benefits of vaccination, and cues to action (OR 4.36; 95% CI 2.35-8.09, and OR 5.49; 95% CI 2.84-10.61, respectively, all P<0.001), but less likely to have the perceived barriers to vaccination (OR 0.19; 95% CI 0.09-0.38; P<0.001) compared with the no acceptance group. Besides, people who had a good knowledge regarding the severity of illness were 3.37 times more likely to have identified as vaccine acceptance (OR 3.37; 95% CI 1.04-10.86, P<0.05). The demographic factors were also associated with willingness to receive the vaccine, with participants who were staff and received COVID-19 information from relatives were less likely to accept the vaccine over those who were doctors and not receiving information from relatives (OR 0.36; 95% CI 0.13-0.96, and OR 0.37; 95% CI 0.17-0.78, respectively, all P<0.05). Conclusions: A rate of willingness to get vaccinated against COVID-19 was relatively high with discrepancies between occupation, receiving information from relatives, knowledge toward the severity of illness, and the elements of Health Belief Model. The findings will provide information for the management authorities to develop relevant interventions to promote COVID-19 vaccination uptake.

Aims: A suitable medium and cultivation parameters have an important role in the improvement of the production of pyocyanin pigment by Pseudomonas aeruginosa microorganism. The study aimed to optimize culture conditions and medium components for maximal pyocyanin production in a recombinant strain P. aeruginosa PS39-phzMS created in previous research. In addition, the process of extraction of pyocyanin was also investigated to select a proper applied solvent for recovering a high amount of pyocyanin as well as its quality. Methodology and results: The pyocyanin purification has based on solvent. Among six tested solvents for extracting pyocyanin out of bacterial broth, two out of six recovered a significant amount of pyocyanin, namely dichloromethane and chloroform, in which chloroform showed a higher pyocyanin yield (25.27 ± 1.02 µg/mL) than dichloromethane (20.26 ± 0.88 µg/mL). The thin-layer chromatography (TLC) of the extracted pyocyanin illustrated a similar to pure pyocyanin with Rf of 0.72 and no mark of other impurity metabolites. The UV-Vis spectra showed a similar peak at 520 nm with pure pyocyanin and the highest peak at 274 nm. Each single culture parameter was studied for the maximal production of pyocyanin. Next, a pyocyanin-producing GM medium was modified on the base of the KingA to find the relative capacity to biosynthesize high pyocyanin yield in P. aeruginosa PS39-phzMS. The results showed that pyocyanin production was the highest in optimal culture conditions, at 30 °C, pH 8, 120 h and agitation of 200 rpm. In the combination of culture condition with the GM, pyocyanin was created at the highest amount of 49.57 µg/mL. Conclusion, significance and impact of study Based on the obtained results of the study, a pyocyanin-producing procedure was optimized, which suggests a promising application to scale-up pyocyanin production by the P. aeruginosa PS39-phzMS.