A Large Retrospective Study of Epidemiological Characteristics of COVID-19 Patients in the North of Iran: Association between SARS-CoV-2 RT-PCR Ct Values with Demographic Data.

Objectives: To avoid worsening from mild, moderate, and severe diseases and to reduce mortality, it is necessary to identify the subpopulation that is more vulnerable to the development of COVID-19 unfavorable consequences. This study aims to investigate the demographic information, prevalence rates of common comorbidities among negative and positive real-time reverse-transcriptase polymerase chain reaction (rRT-PCR) patients, and the association between SARS-CoV-2 cycle threshold (Ct) at hospital admission, demographic data, and outcomes of the patients in a large population in Northern Iran. Methods: This large retrospective cross-sectional study was performed from 7 March to 20 December 2020. Demographic data, including gender, age, underlying diseases, clinical outcomes, and Ct values, were obtained from 8,318 cases suspected of COVID-19, who were admitted to four teaching hospitals affiliated to Babol University of Medical Sciences (MUBABOL), in the north of Iran. Results: Since 7 March 2020, the data were collected from 8,318 cases suspected of COVID-19 (48.5% female and 51.5% male) with a mean age of 53 ± 25.3 years. Among 8,318 suspected COVID-19 patients, 3,250 (39.1%) had a positive rRT-PCR result; 1,632 (50.2%) patients were male and 335 (10.3%) patients died during their hospital stay. The distribution of positive rRT-PCR revealed that most patients (464 (75.7%)) had a Ct between 21 and 30 (Group B). Conclusion: Elderly patients, lower Ct, patients having at least one comorbidity, and male cases were significantly associated with increased risk for COVID-19-related mortality. Moreover, mortality was significantly higher in patients with diabetes, kidney disease, and respiratory disease.

Posttreatment Downregulation of Type III Interferons in Patients with Acute Brucellosis.

There is a limited number of clinical studies on interferon (IFN) levels in human brucellosis. The novel group of interferons, type III interferons, which consists of four IFN-λ (lambda) molecules called IFN-λ1 or interleukin-29 (IL-29), IFN-λ2 or IL-28A, IFN-λ3 or IL-28B, and IFN-λ4, is not fully known. This study is one of the first studies of IL-28A and IL-29 levels in brucellosis cases at the end of their treatment course. A total of 33 acute brucellosis patients were included in this study. We considered changes in the levels of IL-28A and IL-29 in cases with acute brucellosis before and after treatment with standard therapy that referred to the Ayatollah Rohani Hospital in Babol, northern Iran. Of 33 included patients, 22 (66.6%) were males, and 11 (33.4%) were females. The range of patients' age was 49.21 ± 17.70 years. Serum IL-29 and IL-28A (acute form: 56.4 ± 30.32 pg/mL and 48.73 ± 27.72 pg/mL, respectively, and posttreatment: 40.15 ± 20.30 pg/mL and 38.79 ± 22.66 pg/mL, respectively) levels were elevated significantly in acute brucellosis than after treatment (p < 0.05). These findings indicate that considering biomarker levels in brucellosis patients may indicate the chronicity of infection. In conclusion, we suggest that IL-29 and IL-28A levels may be valuable biomarkers for follow-up patients with brucellosis.

Multicenter Cryptococcal Antigen Screening of HIV-Infected Patients in Iran.

Early diagnosis and targeted preemptive antifungal treatment are crucial in reducing cryptococcal meningitis (CM)-related mortality in individuals living with human immunodeficiency virus (HIV). The present study was performed to determine cryptococcal antigenemia and outcomes among HIV-infected patients in Iran. This multicenter prospective study was conducted between October 2016 and December 2018. For the purpose of the study, blood samples were randomly collected from 177 profoundly immunosuppressed (CD4+ counts < 200 cells/µL) HIV-positive individuals in six major cities of Iran. The patients were antiretroviral therapy-naive or had received inadequate medication. The stored sera were screened for cryptococcal antigen (CrAg), using point-of-care lateral flow assay (IMMY® diagnostics, Norman, OK, US). Overall, out of the 174 asymptomatic patients, 3 (1.72%) cases were CrAg-positive using the LFA in serum. Accordingly, the prevalence of cryptococcal antigenemia was 7.14%, 0%, and 1.2% in the patients with the CD4+ counts of < 50, 50-100, and 100-200 cells/µL, respectively. The median age of the patients with antigenemia was 36 years (age range 8-55 years). The median CD4+ count of the cohort was 98 cells/µL (range 14-200 cells/µL). Routine screening of Iranian HIV-infected patients with CD4+ count of < 50 cells/µL before initiating antiretroviral therapy is justified. It is suggested to conduct more inclusive research throughout the whole country on more patients to recommend screening cryptococcal antigen strongly.

Joint modeling of longitudinal and competing risks for assessing blood oxygen saturation and its association with survival outcomes in COVID-19 patients.

BACKGROUND: The objective of the present study is to evaluate the association between longitudinal and survival outcomes in the presence of competing risk events. To illustrate the application of joint modeling in clinical research, we assessed the blood oxygen saturation (SPO2) and its association with survival outcomes in coronavirus disease (COVID-19). MATERIALS AND METHODS: In this prospective cohort study, we followed 300 COVID-19 patients, who were diagnosed with severe COVID-19 in the Rohani Hospital in Babol, the north of Iran from October 22, 2020 to March 5, 2021, where death was the event of interest, surviving was the competing risk event and SPO2 was the longitudinal outcome. Joint modeling analyses were compared to separate analyses for these data. RESULT: The estimation of the association parameter in the joint modeling verified the association between longitudinal outcome SPO2 with survival outcome of death (Hazard Ratio (HR) = 0.33, P = 0.001) and the competing risk outcome of surviving (HR = 4.18, P < 0.001). Based on the joint modeling, longitudinal outcome (SPO2) decreased in hypertension patients (ß = -0.28, P = 0.581) and increased in those with a high level of SPO2 on admission (ß = 0.75, P = 0.03). Also, in the survival submodel in the joint model, the risk of death survival outcome increased in patients with diabetes comorbidity (HR = 4.38, P = 0.026). CONCLUSION: The association between longitudinal measurements of SPO2 and survival outcomes of COVID-19 confirms that SPO2 is an important indicator in this disease. Thus, the application of this joint model can provide useful clinical evidence in the different areas of medical sciences.

Prevalence of Psychological Distress and Posttraumatic Stress Symptoms and Associated Factors in Hospitalized Iranian COVID-19 Patients.

Objectives: To investigate the prevalence of psychiatric symptoms/distress and posttraumatic stress (PTS) and associated factors among inpatients with COVID-19 before discharge from the hospital. Methods: This cross-sectional study was conducted in two teaching referral hospitals in Babol, Iran from July to November 2020. The subjects were inpatients diagnosed with COVID-19 who were clinically stable. Before their discharge from the hospital, the patients completed three questionnaires: demographic data, Brief Symptom Inventory, and Primary Care Post Traumatic Stress Disorder Screen for Diagnostic and Statistical Manual-5. Results: The subjects were 477 inpatients diagnosed with COVID-19 including 40 (8.4%) admitted to intensive care units. Their average age was 60.5±17.9 years; 53.9% were female. Most had symptoms of significant psychological distress (96.0%) and PTS (8.1%) prior to discharge. A higher level of education (-0.18; standard error (SE) = 0.05; p < 0.001) was a negative predictor of psychiatric distress. The admission to intensive care units (0.86; SE = 0.08; p< 0.001) was a positive predictor of psychiatric distress. Conclusions: Most COVID-19 inpatients suffered significant psychiatric distress and PTS symptoms before discharge. Appropriate mental health crisis interventions are recommended for COVID-19 patients during hospitalization.

A Multiple-Center, Retrospective Study of Characteristics and Outcomes of Hospitalized COVID-19 Patients with Cardiovascular Disease in North Iran.

Background: In this retrospective study, we investigated the outcomes and demographic characteristics of COVID-19 patients with and without a history of CVD. Methods: This large retrospective, multicenter study was performed on inpatients with suspected COVID-19 pneumonia who were admitted across four hospitals in Babol, Northern Iran.Demographic data, clinical data, and cycle threshold value (Ct) results of Real Time PCR were obtained. Then, participants were divided into two groups: (1) cases with CVDs, (2) cases without CVDs. Results: A total of 11097 suspected COVID-19 cases with a mean ± SD age of 53 ±25.3 (range: 0 to 99) years were involved in the present study. Out of whom 4599 (41.4%) had a positive RT-PCR result. Of those, 1558 (33.9%) had underlying CVD. Patients with CVD had significantly more co-morbidities such as hypertension, kidney disease, and diabetes. Moreover, 187 (12%) and 281 (9.2%) of patients with and without CVD died, respectively. Also, mortality rate was significantly high among the three groups of Ct value in patients with CVD, with the highest mortality in those with Ct between 10 and 20 (Group A = 19.9%). Conclusions: In summary, our results highlight that CVD is a major risk factor for hospitalization and the severe consequences of COVID-19. Death in CVD group is significantly higher compared to non-CVD. In addition, the results show that age-related diseases can be a serious risk factor for the severe consequences of COVID-19.

Iranian Smell Diagnostic Test in Covid-19 Disease; Report of Covid-19 Center of North of Iran.

Background: SARS-CoV-2 is a pandemic coronavirus that causes the COVID-19 syndrome. In the pandemic of COVID-19 many patients were affected to new onset olfactory dysfunction. Since there is a dearth of research studies regarding the standard smell test, the present study was conducted to fill this gap. Methods: The present retrospective cohort study was conducted on 250 clients with or without diagnosis of Covid-19 disease who referred to Covid-19 centers of North of Iran. Two groups were matched for age and sex. Data were collected by examination, demographic and clinical information questionnaire and Iranian smell diagnostic test. The binary logistic regression to estimate the odds ratio value in SPSS version 23.0 was used. Results: One-hundred cases (42.2%) had hyposmia and 20 cases (8.4%) were found to have anosmia. Type of covid-19 sign and symptom were statistically significant with olfactory dysfunction (41 cases, 31.8%), fever (28 cases, 21.7%), weakness and dyspnea (15 cases, 11.6%), (p=0.0001). The urban residency equal OR=6.42 (3.04-13.53) to rural residency for olfactory dysfunction (p=0.0001). Covid-19 patients' OR=61.25 (27.36-137.11) chance to be affected by the olfactory dysfunction in compare to control group (p=0.0001). Also, with increasing age, chance of olfactory dysfunction changed from OR=0.61(1.16-0.13) to OR=1.89 (0.82-4.33). Furthermore, female chance OR=1.21 (0.72-2.03) and employee patients was OR=2.29 (1.30-4.04) to olfactory dysfunction. Conclusion: Alf of the patients were affected by olfactory dysfunction. Furthermore, Covid-19 patients, urban residency, lower age, female and employee were the prognostic factors for olfactory dysfunction. The standard olfactory tests such as IR-SIT is suggested for screening and detecting the clients probably affected by covid-19 especially in younger ages.

Prognostic accuracy of inflammatory markers in predicting risk of ICU admission for COVID-19: application of time-dependent receiver operating characteristic curves.

OBJECTIVE: Intensive care unit (ICU) admission occurs at different times during hospitalization among patients with COVID-19. We aimed to evaluate the time-dependent receive operating characteristic (ROC) curve and area under the ROC curve, AUC(t), and accuracy of baseline levels of inflammatory markers C-reactive protein (CRP) and neutrophil-to-lymphocyte ratio (NLR) in predicting time to an ICU admission event in patients with severe COVID-19 infection. METHODS: In this observational study, we evaluated 724 patients with confirmed severe COVID-19 referred to Ayatollah Rohani Hospital, affiliated with Babol University of Medical Sciences, Iran. RESULTS: The AUC(t) of CRP and NLR reached 0.741 (95% confidence interval [CI]: 0.661-0.820) and 0.690 (95% CI: 0.607-0.772), respectively, in the first 3 days after hospital admission. The optimal cutoff values of CRP and NLR for stratification of ICU admission outcomes in patients with severe COVID-19 were 78 mg/L and 5.13, respectively. The risk of ICU admission was significantly greater for patients with these cutoff values (CRP hazard ratio = 2.98; 95% CI: 1.58-5.62; NLR hazard ratio = 2.90; 95% CI: 1.45-5.77). CONCLUSIONS: Using time-dependent ROC curves, CRP and NLR values at hospital admission were important predictors of ICU admission. This approach is more efficient than using standard ROC curves.

Evaluation of Time-Varying Biomarkers in Mortality Outcome in COVID-19: an Application of Extended Cox Regression Model.

Background: COVID-19 pandemic has created many challenges for clinicians. The monitoring trend for laboratory biomarkers is helpful to provide additional information to determine the role of those in the severity status and death outcome. Objective: This article aimed to evaluate the time-varying biomarkers by LOWESS Plot, check the proportional hazard assumption, and use to extended Cox model if it is violated. Methods: In the retrospective study, we evaluated a total of 1641 samples of confirmed patients with COVID-19 from October until March 2021 and referred them to the central hospital of Ayatollah Rohani Hospital affiliated with Babol University of medical sciences, Iran. We measured four biomarkers AST, LDH, NLR, and lymphocyte in over the hospitalization to find out the influence of those on the rate of death of COVID-19 patients. Results: The standard Cox model suggested that all biomarkers were prognostic factors of death (AST: HR=2.89, P<0.001, Lymphocyte: HR=2.60, P=0.004, LDH: HR=2.60, P=0.006, NLR: HR=1.80, P<0.001). The additional evaluation showed that the PH assumption was not met for the NLR biomarker. NLR biomarkers had a significant time-varying effect, and its effect increase over time (HR(t)=exp (0.234+0.261×log(t)), p=0.001). While the main effect of NLR did not show any significant effect on death outcome (HR=1.26, P=0.097). Conclusion: The reversal of results between the Cox PH model and the extended Cox model provides insight into the value of considering time-varying covariates in the analysis, which can lead to misleading results otherwise.

One-year prevalence and the association between SARS-CoV-2 cycle threshold, comorbidity and outcomes in population of Babol, North of Iran (2020-2021).

Background: The present study aimed to investigate the one-year prevalence of SARS-CoV-2, common comorbidities and demographic information among negative- and positive rRT-PCR in health care workers (HCW), hospitalized and outpatients. Also, the association between SARS-CoV-2 cycle threshold (Ct) and the outcomes of patients were analyzed in Babol, northern Iran. Methods: This large retrospective cross-sectional study was performed between March 2020 and March 2021. The records of 19232 hospitalized, outpatients and HCW suspected to COVID-19 were collected from teaching hospitals in the North of Iran. Results: Out of the 19232 suspected to COVID-19 patients, 7251 (37.7%) had a positive rRT-PCR result; 652 (9%), 4599 (63.4%) and 2000 (27.6%) of those were categorized as HCW, hospitalized and outpatients, respectively. Moreover, between the hospitalized and the outpatient group, 10.2 and 0.8% cases died, whereas no death cases were reported in the HCW. Furthermore, it seems that death rate was significantly different between the three groups of Ct value, the highest mortality in those with Ct between 21 and 30 (group B=7.6%) and the lowest in the group with the highest Ct (between 31 and 40 = 5.5%) (p<0.001). Conclusion: In summary, 37.7% of cases were positive for SARS-CoV-2; of which, 63.4, 27.6 and 9% were hospitalized, outpatients and HCW, respectively. With regard to the mortality rate in hospitalized patients and the significant association with Ct under 20 and 30, it seems that the early detection and the initial quantification of SARS-CoV-2 in the first week of the conflict and therapeutic considerations to reduce the relative load can reduce the mortality rate.

C-Reactive Protein as a Prognostic Indicator in COVID-19 Patients.

While some biomolecules have been explored to identify potential biomarkers for the prognosis of COVID-19 patients, there is no reliable prognostic indicator of the disease progression and severity. We aimed to evaluate the ability of the C-reactive protein (CRP) to predict COVID-19 infection outcome. This retrospective study was conducted on 429 patients diagnosed with COVID-19 between March 30, 2020, and April 30, 2020. The study population was divided into severe (n = 175) and nonsevere cases (n = 254). Data on demographic characteristics, clinical features, and laboratory findings on admission were collected. The proportion of patients with increased CRP levels was significantly higher in severe cases than in nonsevere patients. Analysis of the receiver operating characteristic (ROC) curve found that CRP could be used as an independent factor in predicting the severity of COVID-19. Also, patients with CRP >64.75 mg/L were more likely to have severe complications. In conclusion, CRP serum levels can predict the severity and progression of illness in patients with COVID-19.

Phenotypic and genotypic detection of metallo-beta-lactamases in Carbapenem resistant Acinetobacter baumannii.

BACKGROUND: Carbapenem resistance in Acinetobacter baumannii has become a major concern for treating physicians. The aim of this study was to investigate the prevalence of metallo ß-lactamase (MBL) genes (bla VIM , and bla IMP) among isolated multidrug-resistant A. baumannii . METHODS: Fifty non-repetitive carbapenem-resistant A. baumannii isolates were collected. Antibiotic susceptibility was performed by disk diffusion method. MICs were determined by E test method. The resistant strains were tested for the production of carbapenemases by the Modified Hodge Test (MHT) followed by EDTA-disk synergy test was performed for metallo-ß-lactamases (MBL) phenotypic detection. Detection of bla VIM , and bla IMP was performed by PCR followed by sequencing. RESULTS: All isolates had a multidrug resistant profile, and were all resistant to all antibiotics including the carbapenems but remained susceptible to colistin. Among these isolates, Carbapenemase production was confirmed by the Modified Hodge test for 42 (84%) isolates. Phenotypic method showed the production of MBL in 15 (30%) isolates. PCR techniques revealed that out of 50 isolates, 13 (26%) were positive for bla VIM and all were negative for bla IMP . CONCLUSION: Our study concludes that the high prevalence of carbapenem resistant Acinetobacter species with MBL production is one of the main concerns in our country and this situation needs strict infection control measures.

Clinical and laboratory findings from patients with COVID-19 pneumonia in Babol North of Iran: a retrospective cohort study.

BACKGROUND: In December 2019, China has experienced an outbreak of novel coronavirus disease 2019 (COVID-19). Coronavirus has now spread to all of the continents. We aimed to consider clinical characteristics, laboratory data of COVID-19 that provided more information for the research of this novel virus. METHODS: We performed a retrospective cohort study on the clinical symptoms and laboratory findings of a series of the 100 confirmed patients with COVID-19. These patients were admitted to the hospitals affiliated to Babol University of Medical Sciences (Ayatollah Rohani, Shahid Beheshti and Yahyanejad hospitals) form 25 February 2020 to 12 March 2020. RESULTS: Nineteen patients died during hospitalization and 81 were discharged. Non-survivor patients had a significantly higher C-reactive protein (CRP) (MD: 46.37, 95% CI: 20.84, 71.90; P = 0.001), white blood cells (WBCs) (MD: 3.10, 95% CI: 1.53, 4.67; P < 0.001) and lower lymphocyte (MD: -8.75, 95% CI: -12.62, -4.87; P < 0.001) compared to survivor patients Data analysis showed that comorbid conditions (aRR: 2.99, 95% CI: 1.09, 8.21, P = 0.034), higher CRP levels (aRR: 1.02, 95% CI: 1.01, 1.03, P = 0.044), and lower lymphocyte (aRR: 0.82, 95% CI: 0.73, 0.93, P = 0.003) were associated with increased risk of death. CONCLUSIONS: Based on our findings, most non-survivors are elderly with comorbidities. Lymphopenia and increased levels of WBCs along with elevated CRP were associated with increased risk of death. Therefore, it is best to be regularly assessed these markers during treatment of COVID-19 patients.

Serum and alveolar procalcitonin had a weak diagnostic value for ventilator-associated pneumonia in patients with pulmonary infection score ≥ 6.

BACKGROUND: Measuring the serum and alveolar procalcitonin level as inflammatory marker in the diagnosis of ventilator-associated pneumonia (VAP) has been taken into account. In this study, serum and alveolar procalcitonin levels in patients with suspected VAP and patients with confirmed VAP were compared. METHODS: This cross-sectional study was conducted using 50 intubated intensive care unit (ICU) patients, connected to ventilator, from October 2014 to April 2015. 50 patients with clinical pulmonary infection score ≥6 were divided into two groups. Patients whose bronchoalveolar lavage (BAL) has shown the growth of more than 104 CFU/mL were included in confirmed VAP group and other patients were included in suspected VAP group. Serum and alveolar procalcitonin levels were measured and compared between both groups. RESULTS: Mean age of patients was 69.10 ± 42.13 with a range of 16-90 years, out of which 23 patients were male (46%) and 27 patients were female (54%). Moreover, patients' mean clinical pulmonary infection score was reported to be 7.02 ± 1.07. There was a significant relationship between serum and alveolar procalcitonin in suspected patients and patients with an approved form of pneumonia (p = 0.001 and 0.027). Area under the curve for alveolar procalcitonin was 0.683 (sensitivity = 57%; specificity = 80%) and for serum procalcitonin 0.751 (sensitivity = 71%; specificity = 73%) for the diagnosis of VAP. CONCLUSION: According to the results of the present study, we can diagnose ventilator-associated pneumonia earlier and more accurately by measuring procalcitonin level (particularly alveolar type) in intensive care unit patients.

Erythema Multiforme as a Result of Orf Disease; a Case Report.

Orf is a mucocutaneous disease that occurs when non-intact skin comes into contact with contaminated sheep saliva. The lesions may complicate to lymphangitis or secondary bacterial infection, but systemic complications such as erythema multiforme, maculopapular rash, and generalized lymphadenopathy are rare. In this paper, we present two cases of erythema multiforme following Orf disease.

The course and outcome of renal failure due to human leptospirosis referred to a hospital in North of Iran; A follow-up study.

BACKGROUND: Renal complication of leptospirosis is common and its clinical manifestations vary from urinary sediment changes to acute renal failure. The aim of this study was to determine the final outcome of renal involvement in leptospirosis. METHODS: This longitudinal prospective study included all serologically confirmed cases of leptospirosis with evidence of renal failure. All patients were followed for three months while all patients with renal failure were followed-up for one year. RESULTS: Fifty-one patients, 53.5±14.8 years (82.4% males) with acute renal failure were studied. Over the hospitalization period, 28 patients recovered, and seven (13.72%) patients died of multiple organ failure. At the time of discharge, 16 patients had mild renal failure. Over the follow-up period, all patients recovered but in two patients renal failure persisted at creatinine level of 1.5 mg/dl. CONCLUSION: Development of renal failure in leptospirosis is not rare. Recovery of renal function may last several months. However, most patients recover completely at least after one year.

Measurement of primary and secondary stability of dental implants by resonance frequency analysis method in mandible.

Background. There is no doubt that the success of the dental implants depends on the stability. The aim of this work was to measure the stability of dental implants prior to loading the implants, using a resonance frequency analysis (RFA) by Osstell mentor device. Methods. Ten healthy and nonsmoker patients over 40 years of age with at least six months of complete or partial edentulous mouth received screw-type dental implants by a 1-stage procedure. RFA measurements were obtained at surgery and 1, 2, 3, 4, 5, 7, and 11 weeks after the implant surgery. Results. Among fifteen implants, the lowest mean stability measurement was for the 4th week after surgery in all bone types. At placement, the mean ISQ obtained with the magnetic device was 77.2 with 95% confidence interval (CI) = 2.49, and then it decreased until the 4th week to 72.13 (95% CI = 2.88), and at the last measurement, the mean implant stability significantly (P value <0.05) increased and recorded higher values to 75.6 (95% CI = 1.88), at the 11th week. Conclusions. The results may be indicative of a period of time when loading might be disadvantageous prior to the 4th week following implant placement. These suggestions need to be further assessed through future studies.

Seroepidemiology of varicella zoster virus in healthcare workers in Babol, Northern Iran.

BACKGROUND: Varicella zoster virus (VZV) infection is one of the nosocomial infections and healthcare workers (HCWs) are at high risk group who work in the hospital with likelihood of varicella acquisition or transmission. This study evaluated the VZV seroprevalence in this high risk population in Babol, Iran. METHODS: Serological testing for VZV using enzyme linked immunosorbent assay (ELISA) was performed on 459 HCWs in Ayatollah Rouhani Hospital, Babol, Northern Iran from 2011 to 2012. A questionnaire was completed including age, gender, place of residence, marital status, history of chickenpox, educational level, working experience and risk of exposure. The data were collected and analyzed. RESULTS: The mean age of these subjects was 32.2±1.1 years. Four hundred-sixteen (90.6%) cases were females and 43 (9.4%) were males. The overall positive seroprevalence of VZV was 94.6%. No statistically significant differences were observed between age, gender, place of residence, risk of exposure, marital status, educational level, working experience and seropositivity. The seropositivity of varicella was seen in 278 (95.5%) of 297 cases with positive history and in 30 (81.1%) of 37 cases who did not (p=0.005). CONCLUSION: The results show that a positive history of VZV is associated with positive seroprevalence but can not be a reliable indicator of the immunity, therefore, serological screening should be considered for all the HCWs.