The COVID-19 pandemic has affected the entire world, resulting in a tremendous change to people’s lifestyles. We investigated the Korean public response to COVID-19 vaccines on social media from 23 February 2021 to 22 March 2021. We collected tweets related to COVID-19 vaccines using the Korean words for “coronavirus” and “vaccines” as keywords. A topic analysis was performed to interpret and classify the tweets, and a sentiment analysis was conducted to analyze public emotions displayed within the retrieved tweets. Out of a total of 13,414 tweets, 3509 were analyzed after preprocessing. Eight topics were extracted using the Latent Dirichlet Allocation model, and the most frequently tweeted topic was vaccine hesitation, consisting of fear, flu, safety of vaccination, time course, and degree of symptoms. The sentiment analysis revealed a similar ratio of positive and negative tweets immediately before and after the commencement of vaccinations, but negative tweets were prominent after the increase in the number of confirmed COVID-19 cases. The public’s anticipation, disappointment, and fear regarding vaccinations are considered to be reflected in the tweets. However, long-term trend analysis will be needed in the future.

Background: The usefulness of the oxygen reserve index (ORi) in reducing hyperoxemia remains unclear. We designed this study to investigate whether fraction of inspired oxygen (FiO 2 ) adjustment under a combination of ORi and peripheral oxygen saturation (SpO 2 ) guidance can reduce intraoperative hyperoxemia compared to SpO 2 alone.Methods: In this prospective, double-blind, randomized controlled study, we allocated patients scheduled for laparoscopic gastrectomy to the SpO 2 group (FiO 2 adjusted to target SpO 2 ≥ 98%) or the ORi-SpO 2 group (FiO 2 adjusted to target 0 < 0 ORi < .3 and SpO 2 ≥ 98%). The ORi, SpO 2 , FiO 2 , arterial partial pressure of oxygen (PaO 2 ), and incidence of severe hyperoxemia (PaO 2 ≥ 200 mm Hg) were recorded before and 1, 2, and 3 hours after surgical incision. Data from 32 and 30 subjects in the SpO 2 and ORi-SpO 2 groups, respectively, were analyzed.Results: PaO 2 was higher in the SpO 2 group (250.31 ± 57.39 mm Hg) than in the ORi-SpO 2 group (170.07 ± 49.39 mm Hg) 1 hour after incision (P < .001). PaO 2 was consistently higher in the SpO 2 group than in the ORi-SpO 2 group, over time (P = .045). The incidence of severe hyperoxemia was higher in the SpO 2 group (84.4%) than in the ORi-SpO 2 group (16.7%, P < .001) 1 hour after incision. Higher FiO 2 was administered to the SpO 2 group [52.5 (50-60)] than the ORi-SpO 2 group [40 (35-50), P < .001] 1 hour after incision. SpO 2 was not different between the 2 groups. Conclusion:The combination of ORi and SpO 2 guided FiO 2 adjustment reduced hyperoxemia compared to SpO 2 alone during laparoscopic gastrectomy.Abbreviations: FiO 2 = fraction of inspired oxygen, ORi = oxygen reserve index, PaO 2 = arterial partial pressure of oxygen, SpO 2 = peripheral oxygen saturation.