Objective:To test the validity and reliability of the Perceived Stress Scale-14 items (PSS-14) applied in cancer survivors.Methods:Totally 652 cancer survivors (patients who had finished active treatments and were in convalescence) were selected and a field questionnaire survey was conducted among them.Exploratory factor analysis and confirmatory factor analysis were performed to test the construct validity of PSS-14.Correlation between the two dimensions (discriminant validity) and correlation between stress and quality of life were analyzed to further test its validity.The intemal consistency reliability,split-half reliability,retest reliability and sensitivity analysis were adopted to test the reliability of PSS-14.Results:Two common factors were extracted in the exploratory factor analysis.The cumulative percentage of variance explained was 60.8％.The index of confirmatory factor analysis were:TLI =0.92,CFI =0.93,SRMR =0.07,RMSEA =0.08.The correlation coefficient between the two dimensions of PSS-14 was-0.16 (P ＜0.001).The correlation coefficients between the score of PSS-14 and each dimension of EORTC QLQ-C30 were 0.24-0.55 (P ＜ 0.001).The Cronbach α coefficients of the whole scale and the two dimensions named "perceived coping ability" and "perceived distress" were 0.78,0.91 and 0.88 respectively.After the scale was split into two parts,the Cronbach α coefficients of each part were 0.66 and 0.60.The Spearman-Brown coefficient was 0.79.The Guttman split-half coefficient was 0.79.After one item was removed from the scale each time,the Cronbach a coefficients of the remaining items varied from 0.75 to 0.77.The retest reliability of the whole scale and the two dimensions were 0.89,0.86 and 0.85 respectively.Conclusion:PSS-14 shows favorable validity and reliability,suggesting the utility to assess stress of cancer survivors as a self-administered inventory.

OBJECTIVETo investigate the associations between physical exercise and quality of life in breast cancer patients.

METHODSA cross-sectional study was conducted among 3 344 community breast cancer patients between April and July 2013 in Shanghai, China. Data were collected using a questionnaire, including socio-demographic situation, cancer survival and health behaviors, and scores of EORTC QLQ-C30 Simplified Chinese version and FACT-G Simplified Chinese version.

RESULTSAmong a total of 3 344 breast cancer patients, the patients doing exercise reported significantly higher EORTC physical functioning scores, role functioning scores, emotional functioning scores, global health scores, and FACT-G physical well-being scores, social well-being scores, emotional well-being scores, functional well-being scores, and FACT-G total scores than the patients who didn't take exercise (P < 0.05, P(Adjusted)<0.05) . Breast cancer patients who did exercise more than or equal to 5 times/week reported significantly higher EORTC role functioning scores, cognitive functioning scores, emotional functioning scores, global health scores and FACT-G physical well-being scores, functional well-being scores, and FACT-G total scores than patients who did exercise less than 5 times/week (P < 0.05, P(Adjusted)<0.05 ).

CONCLUSIONSThere are active associations between physical exercise and quality of life in breast cancer patients. Engagement in physical exercise is beneficial to breast cancer patients with long-term survival.

Asian Continental Ancestry Group ; Breast Neoplasms ; epidemiology ; China ; epidemiology ; Cross-Sectional Studies ; Exercise ; Humans ; Quality of Life ; Surveys and Questionnaires

OBJECTIVETo investigate the associations between vegetables and fruit intake and quality of life in breast cancer patients.

METHODSA total of 3 344 community breast cancer patients were selected through cluster sampling method between April and July 2013, in Shanghai, China. Data were collected using a questionnaire, which included socio-demographic situation, cancer survival and health behaviors(i.e. vegetables or fruit intake, exercise), European Organization for Research and Treatment (EORTC) QLQ-C30 Simplified Chinese version(3rd edition) and Functional Assessment of Cancer Therapy scale (FACT-G) Simplified Chinese version(4th edition) were used to evaluate the quality of life. Crude quality of life scores were compared between groups. Multiple linear models were used to calculate and compare adjusted means of quality of life between groups, controlling relevant factors.

RESULTSAfter adjusting relevant factors, breast cancer patients who ate more than 250 g vegetables reported higher EORTC physical functioning scores, cognitive functioning scores, emotional functioning scores, global health scores than patients who ate equal or less than 250 g vegetables(respectively (80.79 ± 0.85) vs (79.34 ± 0.82), (80.07 ± 1.03) vs (77.84 ± 0.99), (84.17 ± 0.95) vs (82.76 ± 0.92), (65.75 ± 1.50) vs (62.92 ± 1.45)), t values respectively were 2.76, 3.54, 2.40, 3.17, all P values were <0.05; and breast cancer patients who ate more than 250 g vegetables reported higher FACT-G social well-being scores, function well-being scores, FACT-G total scores than patients who ate equal or less than 250 g vegetables (respectively (17.92 ± 0.40) vs (17.31 ± 0.39), (14.86 ± 0.42) vs (14.34 ± 0.40), (74.78 ± 1.01) vs (73.05 ± 0.97)), t values respectively were 2.49, 2.05, 2.90, all P values were <0.05. After adjusting relevant factors, breast cancer patients who ate fruit everyday reported higher EORTC physical functioning scores, role functioning scores, cognitive functioning scores, emotional functioning scores, social functioning scores, global health scores than patients who didn't eat fruit everyday (respectively (80.40 ± 0.82) vs (79.22 ± 0.87), (89.81 ± 1.00) vs (88.06 ± 1.05), (79.78 ± 0.99) vs (77.11 ± 1.04), (84.43 ± 0.92) vs (81.56 ± 0.97), (77.95 ± 1.25) vs (75.56 ± 1.31), (65.48 ± 1.44) vs (61.74 ± 1.51)), t values respectively were 2.15, 2.64, 4.07, 4.71, 2.89, 4.02, all P values were <0.05; and breast cancer patients who ate fruit everyday reported higher FACT-G physical well-being scores, social well-being scores, emotional well-being scores, functional well-being scores, FACT-G total scores than patients who didn't eat fruit everyday(respectively (23.35 ± 0.26) vs (22.85 ± 0.28), (17.91 ± 0.39) vs (16.98 ± 0.41), (18.59 ± 0.22) vs (18.18 ± 0.23), (14.79 ± 0.40) vs (14.17 ± 0.42), (74.71 ± 0.97) vs (72.17 ± 1.02)), t values respectively were 2.92, 3.65, 2.91, 2.35, 4.05 , all P values were <0.05.

CONCLUSIONThere are active associations between vegetables / fruit intake and quality of life in breast cancer patients. Proper diet may help improve quality of life in breast cancer patients.

Breast Neoplasms ; China ; Diet ; Feeding Behavior ; Female ; Fruit ; Humans ; Quality of Life ; Surveys and Questionnaires ; Vegetables

Objective: Sex differences have been observed in many aspects of schizophrenia, including cognitive deficits. Despite extensive research into the relationship between metabolic factors and cognitive deficits in schizophrenia, few studies have explored the potential sex difference in their association. Methods: We recruited 358 schizophrenia patients and 231 healthy controls. The participants underwent measurements of body mass index (BMI), waist circumference, blood pressure, triglycerides, high-density lipoprotein cholesterol, and fasting blood glucose. Metabolic risk factors included abdominal obesity, hypertension, hyperglycemia, and dyslipidemia. A collection of these metabolic risk factors has been defined as metabolic syndrome. These diagnoses were based on the criteria of the National Cholesterol Education Program’s Adult Treatment Panel III. Cognitive performance was measured using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). A descriptive analysis, difference analysis, and linear regression model were used to identify the metabolic risk factors for cognitive function in schizophrenia. Results: Our findings revealed sex differences in the rate of abdominal obesity and hypertension in schizophrenic patients. Additionally, we observed sex differences in the association between metabolic risk factors and cognitive impairment in schizophrenia. Specifically, hyperglycemia was associated with the immediate memory index score of RBANS in male patients, while dyslipidemia was associated with language, attention, delayed memory index scores, and RBANS total score in female patients. Conclusion Our results suggest that sex should be considered when evaluating the impact of metabolic disorders on the cognitive function of schizophrenic patients. Moreover, our study identifies hyperglycemia and dyslipidemia as potential targets for precise treatment by sex stratification, which could benefit the improvement of cognitive impairment in schizophrenic patients.

Objective:To propose a new grading system-the posterior ligament-bone injury classification and severity (PLICS) score for subaxial cervical spine injury, and evaluate its value in guiding the approach selection for subaxial cervical fracture and dislocation.Methods:All of 394 cases of subaxial cervical fracture and dislocation who received single anterior reduction and fixation in our hospital from January 2002 to December 2015 were retrospectively analyzed. According to the inclusion and exclusion criteria, 354 cases were finally included in this study. The Patients experienced internal fixation failure, postoperative kyphosis or interspinal process space dilation during follow-up were included into the failure group. Other patients were included into the successful group. The difference of visual analogue scale (VAS), neck disability index (NDI), ASIA score and PLICS score before and after surgery between the two groups was compared respectively. The PLICS score is composed of left, right and posterior columns. The injury of the posterior column was classified into mild, moderate and severe degrees, with 1-3 points respectively. The evaluation of lateral column injury included ligament and bone structure. The evaluation of ligament injury included: 1 point for the subluxation of the facet joint, 2 points for the dislocation or the facet joint; Fractures of the lateral column was classified into mild, moderate and severe degrees, with 1-3 points respectively. For the evaluation of the lateral column, the highest score of ligament or bone structure injury was reflected as the score of posterior column injury and was taken into the calculation of the final PLICS score.Results:All 354 patients had complete follow-up data, and the average follow-up time was 18.0±4.0 months, including 339 patients of successful group and 15 patients of failure group. At the 12 month follow-up, the average VAS score of the patients in the successful group decreased from 6.9±0.6 before the operation to 1.9±0.6 ( t=22.481, P<0.0001), and the average VAS score of the patients in the failure group decreased from 5.6±1.0 to 1.1±0.3 ( t=77.252, P<0.0001). The difference between the two groups was statistically significant. The NDI score of the successful group was significantly lower than that of the failure group (7.1%±1.2% vs 15.7%±2.7%, t=24.993, P<0.0001). PLICS score in two groups of patients were analyzed. There was a significant difference in PLICS scores between the two groups ( t=8.777, P<0.0001). According to the PLICS score, the ROC operating curve of the failure of internal fixation after anterior-only surgery was determined. The area under the curve was 0.981, and the 95% confidence interval was 0.943, 1.000. When the PLICS score was 6.5, the maximum value of the Jordan index was 0.927, the sensitivity was 0.994, and the specificity was 0.067. Considering the clinical practicality of PLICS score and the different clinical outcomes of the sub-classification groups of the PLICS score=7, we finally set the threshold as PLICS score=7 with the unilateral severe lateral mass fracture. Conclusion:The PLICS score is based on the anatomy of the posterior three-column structure of the subaxial cervical spine. It gives consideration to the bony structures, including bilateral lateral mass, spinous process, lamina, and the ligament structures. What's more, the overall damage severity of the posterior three columns of the subaxial cervical spine was quantified according to the evaluation of the injury characteristics of each column of ligament-bone structure. In this study, PLICS score and clinical efficacy were compared between two groups of patients, and it was finally determined that when PLICS score ≥7 with the unilateral severe lateral mass fracture, the risk of internal fixation failure is higher for anterior-only approach surgery alone. For these patients, anterior and posterior approach surgery may be considered.

Objective To investigate the associations between vegetables and fruit intake and quality of life in breast cancer patients.Methods A total of 3 344 community breast cancer patients were selected through cluster sampling method between April and July 2013, in Shanghai, China.Data were collected using a questionnaire , which included socio-demographic situation , cancer survival and health behaviors ( i.e.vegetables or fruit intake , exercise ) , European Organization for Research and Treatment (EORTC) QLQ-C30 Simplified Chinese version(3rd edition) and Functional Assessment of Cancer Therapy scale(FACT-G)Simplified Chinese version(4th edition) were used to evaluate the quality of life.Crude quality of life scores were compared between groups.Multiple linear models were used to calculate and compare adjusted means of quality of life between groups , controlling relevant factors.Results After adjusting relevant factors , breast cancer patients who ate more than 250 g vegetables reported higher EORTC physical functioning scores , cognitive functioning scores , emotional functioning scores , global health scores than patients who ate equal or less than 250 g vegetables(respectively (80.79 ±0.85) vs (79.34 ±0.82), (80.07 ±1.03) vs (77.84 ±0.99), (84.17 ±0.95) vs (82.76 ±0.92), (65.75 ±1.50) vs (62.92 ± 1.45)), t values respectively were 2.76, 3.54, 2.40, 3.17, all P values were <0.05;and breast cancer patients who ate more than 250 g vegetables reported higher FACT-G social well-being scores , function well-being scores , FACT-G total scores than patients who ate equal or less than 250 g vegetables ( respectively (17.92 ±0.40) vs (17.31 ±0.39), (14.86 ±0.42) vs (14.34 ±0.40), (74.78 ±1.01) vs (73.05 ± 0.97)), t values respectively were 2.49, 2.05, 2.90, all P values were <0.05.After adjusting relevant factors, breast cancer patients who ate fruit everyday reported higher EORTC physical functioning scores , role functioning scores , cognitive functioning scores , emotional functioning scores , social functioning scores , global health scores than patients who didn′t eat fruit everyday ( respectively ( 80.40 ±0.82 ) vs ( 79.22 ± 0.87), (89.81 ±1.00) vs (88.06 ±1.05), (79.78 ±0.99) vs (77.11 ±1.04), (84.43 ±0.92) vs (81.56 ±0.97), (77.95 ±1.25) vs (75.56 ±1.31), (65.48 ±1.44) vs (61.74 ±1.51)), t values respectively were 2.15, 2.64, 4.07, 4.71, 2.89, 4.02, all P values were <0.05; and breast cancer patients who ate fruit everyday reported higher FACT-G physical well-being scores, social well-being scores, emotional well-being scores , functional well-being scores , FACT-G total scores than patients who didn′t eat fruit everyday ( respectively ( 23.35 ±0.26 ) vs ( 22.85 ±0.28 ) , ( 17.91 ±0.39 ) vs ( 16.98 ±0.41 ) , (18.59 ±0.22) vs (18.18 ±0.23), (14.79 ±0.40) vs (14.17 ±0.42), (74.71 ±0.97) vs (72.17 ± 1.02)), t values respectively were 2.92, 3.65, 2.91, 2.35, 4.05 , all P values were <0.05.Conclusion There are active associations between vegetables /fruit intake and quality of life in breast cancer patients.Proper diet may help improve quality of life in breast cancer patients.

Objective To investigate the associations between vegetables and fruit intake and quality of life in breast cancer patients.Methods A total of 3 344 community breast cancer patients were selected through cluster sampling method between April and July 2013, in Shanghai, China.Data were collected using a questionnaire , which included socio-demographic situation , cancer survival and health behaviors ( i.e.vegetables or fruit intake , exercise ) , European Organization for Research and Treatment (EORTC) QLQ-C30 Simplified Chinese version(3rd edition) and Functional Assessment of Cancer Therapy scale(FACT-G)Simplified Chinese version(4th edition) were used to evaluate the quality of life.Crude quality of life scores were compared between groups.Multiple linear models were used to calculate and compare adjusted means of quality of life between groups , controlling relevant factors.Results After adjusting relevant factors , breast cancer patients who ate more than 250 g vegetables reported higher EORTC physical functioning scores , cognitive functioning scores , emotional functioning scores , global health scores than patients who ate equal or less than 250 g vegetables(respectively (80.79 ±0.85) vs (79.34 ±0.82), (80.07 ±1.03) vs (77.84 ±0.99), (84.17 ±0.95) vs (82.76 ±0.92), (65.75 ±1.50) vs (62.92 ± 1.45)), t values respectively were 2.76, 3.54, 2.40, 3.17, all P values were <0.05;and breast cancer patients who ate more than 250 g vegetables reported higher FACT-G social well-being scores , function well-being scores , FACT-G total scores than patients who ate equal or less than 250 g vegetables ( respectively (17.92 ±0.40) vs (17.31 ±0.39), (14.86 ±0.42) vs (14.34 ±0.40), (74.78 ±1.01) vs (73.05 ± 0.97)), t values respectively were 2.49, 2.05, 2.90, all P values were <0.05.After adjusting relevant factors, breast cancer patients who ate fruit everyday reported higher EORTC physical functioning scores , role functioning scores , cognitive functioning scores , emotional functioning scores , social functioning scores , global health scores than patients who didn′t eat fruit everyday ( respectively ( 80.40 ±0.82 ) vs ( 79.22 ± 0.87), (89.81 ±1.00) vs (88.06 ±1.05), (79.78 ±0.99) vs (77.11 ±1.04), (84.43 ±0.92) vs (81.56 ±0.97), (77.95 ±1.25) vs (75.56 ±1.31), (65.48 ±1.44) vs (61.74 ±1.51)), t values respectively were 2.15, 2.64, 4.07, 4.71, 2.89, 4.02, all P values were <0.05; and breast cancer patients who ate fruit everyday reported higher FACT-G physical well-being scores, social well-being scores, emotional well-being scores , functional well-being scores , FACT-G total scores than patients who didn′t eat fruit everyday ( respectively ( 23.35 ±0.26 ) vs ( 22.85 ±0.28 ) , ( 17.91 ±0.39 ) vs ( 16.98 ±0.41 ) , (18.59 ±0.22) vs (18.18 ±0.23), (14.79 ±0.40) vs (14.17 ±0.42), (74.71 ±0.97) vs (72.17 ± 1.02)), t values respectively were 2.92, 3.65, 2.91, 2.35, 4.05 , all P values were <0.05.Conclusion There are active associations between vegetables /fruit intake and quality of life in breast cancer patients.Proper diet may help improve quality of life in breast cancer patients.

Objective:To test and evaluate the reliability and clinical effectiveness of osteoporotic thoracolumbar fracture (OTLF) scoring and classification system.Methods:A multicenter retrospective case series study was conducted to analyze the clinical data of 530 OTLF patients admitted to 8 hospitals including Honghui Hospital Affiliated to Xi'an Jiaotong University from January 2021 to June 2022. There were 212 males and 318 females, aged 55-90 years [(72.6±10.8)years]. There were 4 patients with grade C and 18 with grade D according to American Spinal Injury Association (ASIA) classification. According to the osteoporotic thoracolumbar injury classification and severity (OTLICS) score, all patients had an OTLICS score over 4 points and required surgical treatment. Among them, 410 patients had acute symptomatic OTLF (ASOTLF), including 24 patients with type I, 159 type IIA, 47 type IIB, 31 type IIC, 136 type IIIA, 8 type IIIB, 2 type IV (absence of neurological symptoms) and 3 type IV (presence of neurological symptoms), and 120 patients had chronic symptomatic OTLF (CSOTLF), including 62 patients with type I, 21 type II, 17 type III, 3 type IV (reducible under general anesthesia), 9 type IV (not reducible under general anesthesia), 1 type V (reducible under general anesthesia), 5 type V (presence of neurological symptoms), and 2 type V (not reducible under general anesthesia). Surgical procedures included percutaneous vertebroplasty (PVP), positional repositioning plus PVP, percutaneous kyphoplasty (PKP), posterior open reduction combined with bone graft fusion and bone cement augmented screw internal fixation, posterior open reduction combined with decompression, bone graft fusion and bone cement augmented screw internal fixation, and posterior open reduction combined with osteotomy and orthopedics, bone graft fusion and bone cement augmented screw internal fixation. A weighted Kappa was used to test the interobserver and intraobserver reliability of the OTLICS score, the ASOTLF classification, and the CSOTLF classification. The visual analog scale (VAS), Oswestry disability index (ODI), ASIA classification were compared before, at 1 month after surgery and at the last follow-up. Incidence of postoperative complications was observed.Results:The percentage of mean interobserver agreement for OTLICS staging was 93.4%, with a mean confidence Kappa value of 0.86, and the percentage of mean intraobserver agreement was 93.0%, with a mean confidence kappa value of 0.86. The percentage of mean interobserver agreement for ASOTLF staging was 94.2%, with a mean confidence Kappa value of 0.84, and the percentage of mean intraobserver agreement was 92.5%, with a mean confidence Kappa value of 0.83. The percentage of mean interobserver agreement for CSOTLF subtyping was 91.9%, with a mean confidence Kappa value of 0.80, and the percentage of mean intraobserver agreement was 91.3%, with a mean confidence Kappa value of 0.81. All the patients were followed up for 6-12 months [(9.0±2.1)months]. The VAS and ODI scores were significantly lower in patients with ASOTLF and CSOTLF classifications at 1 month after surgery and at the last follow-up than those before surgery (all P<0.05). The VAS scores in patients with ASOTLF types IIA, IIB, IIC, IIIA, and IV were significantly lower at the last follow-up than that at 1 month after surgery; the ODI scores in patients with ASOTLF types I, IIA, IIB, IIIA, IIIB and IV were significantly lower at the last follow-up than those at 1 month after surgery. The VAS scores in patients with CSOTLF types II, III, IV, and V were significantly lower at the last follow-up than those at 1 month after surgery, and the ODI scores in patients with all CSOTLF types were significantly lower at the last follow-up than those at 1 month after surgery (all P<0.05). Two patients with ASIA grade C recovered to grade D, and the rest recovered to grade E at the last follow-up ( P<0.01). No major vessel or nerve injury or internal fixation failure was found during follow-up. There were 18 patients with cement leakage, none of whom showed relevant clinical symptoms. There were 35 patients with new vertebral fractures, all of whom recovered well after symptomatic treatment. Conclusions:The OTLICS score, ASOTLF classification and CSOTLF classification have a high degree of reliability. Application of stepwise treatment for patients with different levels of injury according to the scoring and classification system can reduce pain, promote recovery of the spinal function, and reduce complications, which is of some significance in guiding the selection of clinical treatment.

[Objective]To investigate the depression status and its influencing factors in HIV/AIDS patients receiving antiviral therapy.[Methods]From July 2022 to September 2022,successive sampling method was used to recruit HIV/AIDS patients receiving antiviral therapy from antiviral treatment institutions in Nanjing,and they were instructed to fill out anonymous questionnaires.The questionnaire collected the basic information of patients,and depression,HIV stigma score and social support level were investigated by Patient Health Questionnaire-9(PHQ-9),Berger HIV stigma scale(BHSS)and Multidimensional Scale of Perceived Social Support(MSPSS).Multivariate Logistic regression was used to an-alyze the influencing factors of depression.[Results]A total of 1879 valid questionnaires were collected in this study,and the detection rate of depression was 50.1%.The results of multivariate logistic analysis showed that compared with patients with middle school or below,the risk of depression was lower for those with postgraduate or above[OR=0.534,95%CI(0.341,0.835),P=0.006].Compared with antiviral therapy duration<1 year,antiviral therapy duration for 1 to 5 years[OR=0.729,95%CI(0.536,0.991)],>5 to 10 years[OR=0.516,95%CI(0.379,0.702)],>10 years[OR=0.603,95%CI(0.375,0.969)]was associated with a lower risk of depression.High level of social support was a protective factor for depression in HIV/AIDS patients compared with middle and low level of social support[OR=0.430,95%CI(0.349,0.530),P<0.001].There was a higher risk of depression with side effects than without side effects[OR=2.260,95%CI(1.833,2.786),P<0.001].The higher the score on the HIV stigma scale,the higher the possibility of depression was.[Conclusion]The detection rate of depression of patients receiving antiviral therapy in Nanjing is high.After starting antivi-ral therapy,we should strengthen the monitoring of side effects and psychological status of patients,carry out psychologi-cal intervention,alleviate psychological problems,and improve the quality of life of patients receiving antiviral therapy.

:To predict the epidemiological trend of coronavirus disease 2019 (COVID-19) by mathematical modeling based on the population mobility and the epidemic prevention and control measures. : As of February 8，2020，the information of 151 confirmed cases in Yueqing，Zhejiang province were obtained，including patients' infection process，population mobility between Yueqing and Wuhan，etc. To simulate and predict the development trend of COVID-19 in Yueqing, the study established two-stage mathematical models，integrating the population mobility data with the date of symptom appearance of confirmed cases and the transmission dynamics of imported and local cases. : It was found that in the early stage of the pandemic，the number of daily imported cases from Wuhan (using the date of symptom appearance) was positively associated with the number of population travelling from Wuhan to Yueqing on the same day and 6 and 9 days before that. The study predicted that the final outbreak size in Yueqing would be 170 according to the number of imported cases estimated by consulting the population number travelling from Wuhan to Yueqing and the susceptible-exposed-infectious-recovered (SEIR) model; while the number would be 165 if using the reported daily number of imported cases. These estimates were close to the 170，the actual monitoring number of cases in Yueqing as of April 27，2020. : The two-stage modeling approach used in this study can accurately predict COVID-19 epidemiological trend.
COVID-19 ; China/epidemiology* ; Disease Outbreaks ; Humans ; Models, Theoretical ; Pandemics ; SARS-CoV-2