The effect of a soft active back support exosuit on trunk motion and thoracolumbar spine loading during squat and stoop lifts.

Back support exosuits aim to reduce tissue demands and thereby risk of injury and pain. However, biomechanical analyses of soft active exosuit designs have been limited. The objective of this study was to evaluate the effect of a soft active back support exosuit on trunk motion and thoracolumbar spine loading in participants performing stoop and squat lifts of 6 and 10 kg crates, using participant-specific musculoskeletal models. The exosuit did not change overall trunk motion but affected lumbo-pelvic motion slightly, and reduced peak compressive and shear vertebral loads at some levels, although shear increased slightly at others. This study indicates that soft active exosuits have limited kinematic effects during lifting, and can reduce spinal loading depending on the vertebral level. These results support the hypothesis that a soft exosuit can assist without limiting trunk movement or negatively impacting skeletal loading and have implications for future design and ergonomic intervention efforts.

Back support exosuits have the potential to reduce musculoskeletal workplace injuries. We examined and modelled the impact of a soft active exosuit on spine motion and loading. The exosuit generally reduced vertebral loading and did not inhibit trunk motion. Results of this study support future research to examine the exosuit as an ergonomic intervention.

Evaluating adaptiveness of an active back exosuit for dynamic lifting and maximum range of motion.

Back exosuits deliver mechanical assistance to reduce the risk of back injury, however, minimising restriction is critical for adoption. We developed the adaptive impedance controller to minimise restriction while maintaining assistance by modulating impedance based on the user's movement direction and nonlinear sine curves. The objective of this study was to compare active assistance, delivered by a back exosuit via our adaptive impedance controller, to three levels of assistance from passive elastics. Fifteen participants completed five experimental blocks (4 exosuits and 1 no-suit) consisting of a maximum flexion and a constrained lifting task. While a higher stiffness elastic reduced back extensor muscle activity by 13%, it restricted maximum range of motion (RoM) by 13°. The adaptive impedance approach did not restrict RoM while reducing back extensor muscle activity by 15%, when lifting. This study highlights an adaptive impedance approach might improve usability by circumventing the assistance-restriction trade-off inherent to passive approaches.Practitioner summary: This study demonstrates a soft active exosuit that delivers assistance with an adaptive impedance approach can provide reductions in overall back muscle activity without the impacts of restricted range of motion or perception of restriction and discomfort.

Reducing Back Exertion and Improving Confidence of Individuals with Low Back Pain with a Back Exosuit: A Feasibility Study for Use in BACPAC.

OBJECTIVE: Low back pain (LBP) is hallmarked by activity limitations, especially for tasks involving bending. Back exosuit technology reduces low back discomfort and improves self-efficacy of individuals with LBP during bending and lifting tasks. However, the biomechanical efficacy of these devices in individuals with LBP is unknown. This study sought to determine biomechanical and perceptual effects of a soft active back exosuit designed to assist individuals with LBP sagittal plane bending. To understand patient-reported usability and use cases for this device. METHODS: Fifteen individuals with LBP performed two experimental lifting blocks once with and without an exosuit. Trunk biomechanics were measured by muscle activation amplitudes, and whole-body kinematics and kinetics. To evaluate device perception, participants rated task effort, low back discomfort, and their level of concern completing daily activities. RESULTS: The back exosuit reduced peak back extensor: moments by 9%, and muscle amplitudes by 16% when lifting. There were no changes in abdominal co-activation and small reductions maximum trunk flexion compared to lifting without an exosuit. Participants reported lower task effort, back discomfort, and concern about bending and lifting with an exosuit compared to without. CONCLUSIONS: This study demonstrates a back exosuit not only imparts perceptual benefits of reduced task effort, discomfort, and increased confidence in individuals with LBP but that it achieves these benefits through measurable biomechanical reductions in back extensor effort. The combined effect of these benefits implies back exosuits might be a potential therapeutic aid to augment physical therapy, exercises, or daily activities.

Immune Responses After Vaccination With Primary 2-Dose ChAdOx1 Plus a Booster of BNT162b2 or Vaccination With Primary 2-Dose BNT162b2 Plus a Booster of BNT162b2 and the Occurrence of Omicron Breakthrough Infection.

BACKGROUND: Before the omicron era, health care workers were usually vaccinated with either the primary 2-dose ChAdOx1 nCoV-19 (Oxford-AstraZeneca) series plus a booster dose of BNT162b2 (Pfizer-BioNTech) (CCB group) or the primary 2-dose BNT162b2 series plus a booster dose of BNT162b2 (BBB group) in Korea. METHODS: The two groups were compared using quantification of the surrogate virus neutralization test for wild type severe acute respiratory syndrome coronavirus 2 (SVNT-WT), the omicron variant (SVNT-O), spike-specific IgG, and interferon-gamma (IFN-γ), as well as the omicron breakthrough infection cases. RESULTS: There were 113 participants enrolled in the CCB group and 51 enrolled in the BBB group. Before and after booster vaccination, the median SVNT-WT and SVNT-O values were lower in the CCB (SVNT-WT [before-after]: 72.02-97.61%, SVNT-O: 15.18-42.29%) group than in the BBB group (SVNT-WT: 89.19-98.11%, SVNT-O: 23.58-68.56%; all P < 0.001). Although the median IgG concentrations were different between the CCB and BBB groups after the primary series (2.677 vs. 4.700 AU/mL, respectively, P < 0.001), they were not different between the two groups after the booster vaccination (7.246 vs. 7.979 AU/mL, respectively, P = 0.108). In addition, the median IFN-γ concentration was higher in the BBB group than in the CCB group (550.5 and 387.5 mIU/mL, respectively, P = 0.014). There was also a difference in the cumulative incidence curves over time (CCB group 50.0% vs. BBB group 41.8%; P = 0.045), indicating that breakthrough infection occurred faster in the CCB group. CONCLUSION: The cellular and humoral immune responses were low in the CCB group so that the breakthrough infection occurred faster in the CCB group than in the BBB group.

SARS-CoV-2 Omicron escapes mRNA vaccine booster-induced antibody neutralisation in patients with autoimmune rheumatic diseases: an observational cohort study.

OBJECTIVES: This study investigates whether COVID-19 vaccines can elicit cross-reactive antibody responses against the Omicron variant in patients with autoimmune rheumatic diseases (ARDs). METHODS: This observational cohort study comprised 149 patients with ARDs and 94 healthcare workers (HCWs). Blood samples were obtained at enrolment, a median of 15 weeks after the second vaccine dose or 8 weeks after the third dose. The functional cross-neutralisation capacity of sera was measured using the Omicron variant receptor-binding domain-ACE2 binding inhibition assay. We assessed the incidence of breakthrough infections and the potential correlation with neutralising responses in participants after receiving third doses. The association of time-from-vaccine and neutralising responses in sera was predicted using linear regression analysis. RESULTS: The mean cross-neutralising responses against the Omicron variant developed after the second dose was 11.5% in patients with ARDs and 18.1% in HCWs (p=0.007). These responses were significantly lower in patients with ARDs than in HCWs after the third dose (26.8% vs 50.3%, p<0.0001). Only 39.2% of the patient sera showed functional neutralisation capacity to the Omicron variant and cross-neutralising responses were shown to be poorly correlated with anti-spike immunoglobulin G titres. Within 6 weeks of immunological assessments, significantly lower Omicron-neutralising responses were detected in sera from patients with ARDs who developed breakthrough infections compared with those who did not (p=0.018). Additionally, a relative decline was implied in neutralising responses against the Omicron variant as a reference to the wild-type virus during 120 days since the third vaccination, with a predicted decay rate of -0.351%/day (95% CI, -0.559 to -0.144, p=0.001). CONCLUSIONS: Striking antibody evasion manifested by the Omicron variant in patients with ARDs and current vaccine-induced immunity may not confer broad protection from Omicron breakthrough infection, highlighting the need for further research on vaccine effectiveness in patients with immune dysfunctions.

Rhinovirus Incidence Rates Indicate We Are Tired of Non-pharmacological Interventions Against Coronavirus Disease 2019.

BACKGROUND: During the coronavirus disease 2019 (COVID-19) pandemic, the incidence of rhinovirus (RV) is inversely related to the intensity of non-pharmacological interventions (NPIs), such as universal mask wearing and physical distancing. METHODS: Using RV surveillance data, changes in the effect of NPIs were investigated in South Korea during the pandemic. The time to the first visible effect of NPIs after the onset of NPIs (T1), time to the maximum effect (T2), and duration of the maximum effect (T3) were measured for each surge. For each week, the RVdiff [(RV incidence during the pandemic) - (RV incidence within 5 years before the pandemic)] was calculated, and number of weeks for RVdiff to be below zero after NPIs (time to RVdiff ≤ 0) and number of weeks RVdiff remains below zero after NPIs (duration of RVdiff ≤ 0) were measured for each surge. RESULTS: During the study period, four surges of COVID-19 were reported. As the pandemic progressed, T1 and T2 increased, but T3 decreased. Additionally, the "time to RVdiff of ≤ 0" increased and "duration of RVdiff of ≤ 0" decreased. These changes became more pronounced during the third surge (mid-November 2020), before the introduction of the COVID-19 vaccine, and from the emergence of the delta variant. CONCLUSION: The effect of NPIs appears slower, the duration of the effect becomes shorter, and the intensity also decreases less than a year after the onset of the pandemic owing to people's exhaustion in implementing NPIs. These findings suggest that the COVID-19 response strategy must be completely overhauled.

Dual respiratory virus detection in adult patients with acute respiratory illness.

BACKGROUND: Nonrandom multiple respiratory virus (RV) detection provides evidence for viral interference among respiratory viruses. However, little is known as to whether it occurs randomly. METHODS: The prevalence of dual RV detection (DRVD) in patients with acute respiratory illnesses (ARIs) at 4 academic medical centers was investigated; data about the prevalence of 8 RVs were collected from the Korean national RV surveillance dataset. Linear regression analysis was performed to assess the correlation between observed and estimated prevalence of each type of DRVD. RESULTS: In total, 108 patients with ARIs showing DRVD were included in this study between 2011 and 2017. In several types of regression analysis, a strong correlation was observed between the observed and estimated prevalence of each type of DRVD. Excluding three DRVD types (influenza/picornavirus, influenza/human metapneumovirus, and adenovirus/respiratory syncytial virus), the slope of the regression line was higher than that of the line of random occurrence (1.231 > 1.000) and the 95% confidence interval of the regression line was located above the line of random occurrence. CONCLUSIONS: Contrary to the results of previous epidemiologic studies, most types of DRVD occur more frequently than expected from the prevalence rates of individual RV, except for three underrepresented pairs above.

Changes in the early mortality of adult patients with carbapenem-resistant Acinetobacter baumannii bacteremia during 11 years at an academic medical center.

BACKGROUND: In the past decade, carbapenem-resistant Acinetobacter baumannii (CRAB) has emerged as a major pathogen of serious infections in critically ill adult patients. Despite very limited antimicrobial options, clinicians have sought to reduce the mortality of patients with serious CRAB infections. To determine whether these long-term efforts effectively lessened the mortality of such patients, we investigated changes in the early mortality of adult patients with CRAB bacteremia and related clinical factors. METHODS: We reviewed clinical data from 111 adult patients with monomicrobial CRAB bacteremia admitted to an academic medical center between 2006 and 2016. RESULTS: The 14-day mortality rate from 2013 to 2016 was lower than that from 2009 to 2012 (43.4% vs. 71.1%, p = 0.01). When the clinical characteristics of adult patients with CRAB bacteremia from 2013 to 2016 were compared to those of the patients from 2009 to 2012, chronic lung disease (6.7% vs. 24.4%, p = 0.01), a recent history of mechanical ventilation (38.3% vs. 57.8%, p = 0.048), and pneumonia (48.3% vs. 68.9%, p = 0.04) were less frequent in 2013-2016, while neurological disease (43.3% vs. 22.2%, p = 0.02), central venous catheter infection (20.0% vs. 6.7%, p = 0.05), and early appropriate antimicrobial therapy (46.7% vs. 24.4%, p = 0.01) were more frequent. CONCLUSION: The 14-day mortality rate of adult patients with CRAB bacteremia was reduced during 2013-2016. This decrease was associated with early appropriate antimicrobial therapy and a lower proportion of patients with bacteremic pneumonia, which seemed to result from improved hospital infection control during that time period.

Usefulness of national respiratory virus surveillance data for clinicians who manage adult patients.

The Korean Centers for Disease Control and Prevention (KCDC) provides weekly respiratory virus (RV) surveillance reports on its website (the KCDC data). Clinicians in clinical settings wherein the use of PCR for RVs is not a routine laboratory test for adult patients with acute respiratory illness (ARI) may question the clinical utility of such a national RV surveillance dataset in predicting RV outbreaks among their adult patients. We compared the KCDC data to the RV PCR data of adult patients who visited a tertiary care center. During a period of 108 weeks, a total of 6955 (5598 pediatric and 1257 adult) patients underwent RV PCR tests for ARI; most of these tests were administered while the patients were admitted (n = 6,920; 99.5%). From the KCDC website, we collected the RV PCR test results of 22 540 patients. Three graphs of weekly positivity rates were made for adults, children, and the KCDC data per each RV, and these graphs were then compared with one another. Whereas RV outbreaks were coincident between the KCDC and the adult graph with respect to influenza virus, respiratory syncytial virus, human metapneumovirus, and human coronavirus, the same was not true for human bocavirus, parainfluenza virus, rhinovirus, and adenovirus. However, a negative predictive value of the KCDC data in the prediction of the occurrence of an outbreak in the adult graph was high for the respective eight RVs (85-100%). A national RV surveillance dataset may be useful in identifying RV outbreaks in adult patients with severe ARI.

Safety and Effectiveness of Peramivir in Korean Adult Influenza Patients: Prospective Observational Study Based on Post-Marketing Surveillance Data.

BACKGROUND: The safety and clinical effectiveness data of peramivir in the real clinical field are limited. A prospective observational study was conducted based on the post-marketing surveillance data to evaluate the post-marketing safety and effectiveness of peramivir in Korean adults with seasonal influenza. METHODS: Among adults aged 20 years or older who were diagnosed with influenza A or B, patients who started peramivir within 48 hours from the initial symptoms of influenza were enrolled. All adverse events (AEs) that occurred within 7 days after administration of peramivir were checked. For the evaluation of effectiveness, changes in the severity of influenza symptoms and daily living performance were examined before and 7 days after the administration of peramivir. The date on which influenza related symptoms disappeared was checked. RESULTS: A total of 3,024 patients were enrolled for safety evaluation and 2,939 patients were for effectiveness evaluation. In the safety evaluation, 42 AEs were observed in 35 (1.16%) patients. The most common AE was fever. AEs were mostly rated as mild in severity. Serious AEs were observed in 10 patients and two of them died. However, both deaths were considered to be less relevant to peramivir. In the effectiveness evaluation, the severity of influenza symptoms decreased by 10.68 ± 4.01 points and daily living performance was improved 5.59 ± 2.16 points. Influenza related symptoms disappeared on average 3.02 ± 2.39 days after peramivir administration. CONCLUSION: Peramivir showed a tolerable safety profile and acceptable effectiveness in Korean adult patients with seasonal influenza.

Health care-associated acute pyelonephritis is associated with inappropriate empiric antibiotic therapy in the ED.

BACKGROUND: Acute pyelonephritis (APN) is one of the most common bacterial infections. Because health care-associated (HCA) infections in the community setting have similar characteristics to hospital-acquired infections, HCA infections should be distinguished from community-acquired (CA) infections. However, the impact of HCA-APN on treatment outcomes has not been clearly defined. This study aimed to analyze the impact of HCA-APN on the appropriateness of empiric antibiotic therapy and outcomes in community-onset APN. METHODS: We prospectively identified women older than 18years who were hospitalized with APN via the emergency department and whose urine culture grew bacteria at 10 acute care hospitals in South Korea. RESULTS: Of the 388 APN episodes that were included, 99 (25.5%) were HCA-APN and 289 (74.5%) were CA-APN. Compared with patients with CA-APN, patients with HCA-APN had comorbid conditions and septic shock more frequently. Health care-associated APN was caused by resistant uropathogens more often. Patients with HCA-APN had poorer outcomes (ie, early/final clinical and microbiologic failures); however, this was not statistically significant. Patients with HCA-APN had significantly longer hospital stays than did patients with CA-APN. In the multivariable logistic regression analysis for inappropriate empiric therapy, HCA-APN (odds ratio, 1.96; 95% confidence interval, 1.07-3.57; P=.03) and being bed-ridden (odds ratio, 3.04; 95% confidence interval, 1.31-7.07; P=.01) were significant. CONCLUSIONS: Health care-associated APN was associated with inappropriate empiric antibiotic therapy, which might lead to worse outcomes. These HCA factors should be considered when prescribing empiric antibiotic therapy in patients with community-onset APN.

Clinical relevance of multiple respiratory virus detection in adult patients with acute respiratory illness.

Because increasing numbers of nasopharyngeal swab specimens from adult patients with acute respiratory illness (ARI) are being tested by respiratory virus (RV) multiplex reverse transcriptase PCR (RVM-RT-PCR), multiple RV detection (MRVD) is being encountered more frequently. However, the clinical relevance of MRVD in adult patients has rarely been evaluated. The clinical characteristics of hospitalized adult patients with ARI and MRVD by RVM-RT-PCR tests were compared to those of patients with single RV detection (SRVD) during a single year at a tertiary care center. MRVD was observed in 26 of the 190 adult patients (13.7%). The patients with MRVD had a higher incidence of chronic lung disease than the patients with SRVD (34.6% versus 15.9%, crude odds ratio [OR]=2.81, 95% confidence interval [CI]=1.13 to 6.98, P=0.03). Although the former were more likely than the latter to receive mechanical ventilation (19.2% versus 6.7%, crude OR=3.31, 95% CI=1.05 to 10.47, P=0.049), the length of hospital stay (median, 7 versus 6.5 days; P=0.66), and the in-hospital mortality rate (7.7% versus 4.3%, crude OR=1.87, 95% CI=0.37 to 9.53, P=0.35) were not different between the two groups. In multivariate analysis, chronic lung disease was associated with MRVD (adjusted OR=3.08, 95% CI=1.12 to 8.46, P=0.03). In summary, it was not uncommon to encounter adult patients with ARI and MRVD by RVM-RT-PCR tests of nasopharyngeal swab specimens. MRVD was associated with chronic lung disease rather than the severity of the ARI.

Musculoskeletal models determine the effect of a soft active exosuit on muscle activations and forces during lifting and lowering tasks.

Exosuits have the potential to mitigate musculoskeletal stress and prevent back injuries during industrial tasks. This study aimed to 1) validate the implementation of a soft active exosuit into a musculoskeletal model of the spine by comparing model predicted muscle activations versus corresponding surface EMG measurements, and 2) evaluate the effect of the exosuit on peak back and hip muscle forces. Fourteen healthy participants performed squat and stoop lift and lower tasks with boxes of 6 and 10 kg, with and without wearing a 2.7 kg soft active exosuit. Participant-specific musculoskeletal models, which included the exosuit, were created in OpenSim. Model validation focused on the back and hip extensors, where temporal agreement between EMG and model estimated muscle activity was generally strong to excellent (average cross-correlation coefficients ranging from 0.84 to 0.98). Root mean square errors of muscle activity (0.05-0.10) were similar with and without the exosuit, and compared well to prior model validation studies without the exosuit (average root mean square errors ranging from 0.05 to 0.19). In terms of performance, the exosuit reduced the estimated peak erector spinae forces during lifting and lowering phases across all lifting tasks but reduced peak hip extensor muscles forces only in a squat lift task of 10 kg. These reductions in total peak muscle forces were approximately 1.7-4.2 times greater than the corresponding exosuit assistance force, which were 146 ± 19 N and 102 ± 14 N at the times of peak erector spinae forces in lifting and lowering, respectively. Overall, the results support the hypothesis that exosuits reduce soft tissue loading, and thereby potentially reduce fatigue and injury risk during manual materials handling tasks. Incorporating exosuits into musculoskeletal models is a valid approach to understand the impact of exosuit assistance on muscle activity and forces.

The impact of early adequate antimicrobial therapy on 14-day mortality in patients with monomicrobial Pseudomonas aeruginosa and Acinetobacter baumannii bacteremia.

The impact of colistin therapy for early adequate antimicrobial therapy on clinical outcomes has rarely been evaluated in patients with Pseudomonas aeruginosa bacteremia (PAB) or Acinetobacter baumannii bacteremia (ABB). We investigated the impact of early adequate antimicrobial therapy on 14-day mortality in 149 patients with monomicrobial PAB and ABB at two medical centers where colistin treatment was frequently used. Patients who survived the first 14 days of PAB/ABB received adequate antimicrobial therapy within 3 days of bacteremia more frequently than those who died (53.3 vs. 38.6%), although this finding is not statistically significant (p = 0.10). After excluding patients who received adequate colistin therapy, the difference was statistically significant (94.6 vs. 58.8%, p = 0.001). In a multiple regression model excluding patients who received colistin therapy, adequate antimicrobial therapy within 3 days of bacteremia was a preventive factor for 14-day mortality (adjusted OR = 0.23, 95% CI = 0.07-0.80, p = 0.02). In another multiple regression model including patients who received colistin, compared to inadequate antimicrobial therapy, adequate non-colistin therapy was a preventive factor for 14-day mortality (aOR = 0.22, 95% CI = 0.07-0.78, p = 0.019), but adequate colistin therapy was not (aOR = 8.20, 95% CI = 1.07-62.90, p = 0.043). The favorable impact of early adequate antimicrobial therapy on 14-day mortality in patients with monomicrobial PAB/ABB may be lessened in the clinical practice of using colistin frequently. Further studies may be needed to evaluate the clinical impact of colistin therapy in patients with PAB or ABB.

Cytokine and Chemokine Profiles in Acute Severe Fever with Thrombocytopenia Syndrome and Scrub Typhus in South Korea.

In East Asia, severe fever with thrombocytopenia syndrome (SFTS) and scrub typhus, which are common endemic tick- and mite-mediated diseases sharing common clinical manifestations, are becoming public health concerns. However, there are limited data on the comparative immunopathogenesis between the two diseases. We compared the cytokine profiles of SFTS and scrub typhus to further elucidate immune responses that occur during the disease courses. We prospectively enrolled 44 patients with confirmed SFTS and 49 patients with scrub typhus from July 2015 to December 2020. In addition, 10 healthy volunteers were enrolled as healthy controls. A cytometric bead array was used to analyze plasma samples for 16 cytokines. A total of 68 plasma samples, including 31 (45.6%) from patients with SFTS and 37 (54.4%) from patients with scrub typhus, were available for cytokine measurement. There were three cytokine expression patterns: increased levels in both SFTS and scrub typhus (interleukin 6 [IL-6], IL-10, interferon gamma induced protein 10 [IP-10], and granulocyte-macrophage colony-stimulating factor [GM-CSF]), highest levels in SFTS (interferon alpha [IFN-α], IFN-γ, granulocyte-CSF [G-CSF], monocyte chemotactic protein 1 [MCP-1], macrophage inflammatory protein 1α [MIP-1α], and IL-8), and distinct levels in scrub typhus (IL-12p40, tumor necrosis factor alpha [TNFα], IL-1ß, regulated on activation and normally T-cell expressed and secreted [RANTES], IL-17A, and vascular endothelial growth factor [VEGF]). Although patients with acute SFTS and scrub typhus exhibited partly shared expression patterns of cytokines related to disease severity, the different profiles of cytokines and chemokines might contribute to higher mortality in SFTS than in scrub typhus. Discrete patterns of helper T cell-related cytokines and VEGF might reflect differences in CD4 T-cell responses and vascular damage between these diseases.

A study on changes in lung function, neutralizing antibodies, and symptoms of adult patients hospitalized with COVID-19.

BACKGROUND/AIMS: To identify changes in symptoms and pulmonary sequelae in patients with coronavirus disease 2019 (COVID-19). METHODS: Patients with COVID-19 hospitalized at seven university hospitals in Korea between February 2020 and February 2021 were enrolled, provided they had ≥ 1 outpatient follow-up visit. Between January 11 and March 9, 2021 (study period), residual symptom investigations, chest computed tomography (CT) scans, pulmonary function tests (PFT), and neutralizing antibody tests (NAb) were performed at the outpatient visit (cross-sectional design). Additionally, data from patients who already had follow-up outpatient visits before the study period were collected retrospectively. RESULTS: Investigation of residual symptoms, chest CT scans, PFT, and NAb were performed in 84, 35, 31, and 27 patients, respectively. After 6 months, chest discomfort and dyspnea persisted in 26.7% (4/15) and 33.3% (5/15) patients, respectively, and 40.0% (6/15) and 26.7% (4/15) patients experienced financial loss and emotional distress, respectively. When the ratio of later CT score to previous ones was calculated for each patient between three different time intervals (1-14, 15-60, and 61-365 days), the median values were 0.65 (the second interval to the first), 0.39 (the third to the second), and 0.20 (the third to the first), indicating that CT score decreases with time. In the high-severity group, the ratio was lower than in the low-severity group. CONCLUSION: In COVID-19 survivors, chest CT score recovers over time, but recovery is slower in severely ill patients. Subjects complained of various ongoing symptoms and socioeconomic problems for several months after recovery.