375J Contemp Med Sci | Vol. 8, No. 6, November-December 2022: 375–381 Original Characterization of COVID-19 Hospitalized Adult Patients, Vaccinated vs Non-vaccinated in Duhok Province Paiman Abdulsalam Mohammed1*, Muayad Aghali Merza2,3,4 1Directorate of General Health, Duhok, Kurdistan Region, Iraq. 2COVID-19 health facilities, Duhok, Kurdistan Region, Iraq. 3Department of Internal Medicine, Azadi Teaching Hospital, Duhok, Kurdistan Region, Iraq. 4Dean, College of Pharmacy, University of Duhok, Duhok, Kurdistan Region, Iraq. *Correspondence to: Paiman Abdulsalam Mohammed, (E-mail: paimanabdulsalam@yahoo.com) (Submitted: 11 July 2022 – Revised version received: 18 August 2022 – Accepted: 09 October 2022 – Published online: 26 December 2022) Abstract Objectives: First, to determine prevalence of vaccinated COVID-19 patients among hospitalized patients; second, to determine the epidemiological, clinical, and laboratory characteristics of vaccinated and unvaccinated COVID-19 patients. Methods: The study was carried out on 300 adult COVID-19 hospitalized patients at Duhok COVID-19 health facilities. A prospective cross- sectional study was used as the study design. Between October 1, 2021, and March 31, 2022, all patients with PCR-confirmed COVID-19 were enrolled. Results: The majority of people in this study were unvaccinated. Pfizer was most popular among people who had received vaccination. The majority of hospitalized patients were old ages, the mean age was 60.73 ± 15.83 yr. In our study, the unvaccinated females had higher infection rates while vaccinated males had higher hospital admission rates. In our study, vaccinated patients had shorter hospital duration stays. In both vaccinated and unvaccinated patients, predominated cases were severe cases. D dimer was significantly higher among vaccinated patients. The mortality rate was relatively high among both groups. Patients who had received vaccinations tended to experience vomiting and flu-like symptoms more frequently than those who had not. In terms of comorbidities, smoking and malignancy were significant risk factors for COVID-19 infection in unvaccinated patients. Conclusion: We looked at 300 COVID-19 hospitalized patients. In this study, the majority of people were unvaccinated. Pfizer, had higher prevalence among vaccinated individuals. Majority were elderly. The unvaccinated cases had a higher rate of female hospital admissions than male. The D.Dimer level was significantly different between the two groups. Vomiting and flu-like illness showed higher prevalence in vaccinated cases with significant difference. Smoking and malignancy were significant risk factors for COVID-19 infection in unvaccinated patients. In the fight against a public health disaster like a COVID-19 pandemic, the availability of a COVID-19 vaccines campaign are crucial. Keywords: COVID-19, vaccinated, unvaccinated ISSN 2413-0516 Introduction The World Health Organization (WHO) declared the coro- navirus disease 2019 (COVID-19) a pandemic on March 11, 2020. (WHO).1 Globally, severe acute respiratory syn- drome coronavirus 2 (SARSCoV2), the causative agent of COVID-19 has infected tens of millions of people with sig- nificant mortality. The virus is transmitted mainly through exposure to respiratory excretions carrying SARS-CoV-2.2 The clinical manifestation ranges from asymptomatic infec- tion to serious life-threatening condition. Mild cases con- stitute approximately 81%., while severe and critical cases constitute 14% and 5%, respectively.3 SARS-CoV-2 has a particular tendency to involve the lower respiratory tract, resulting in a hazardous complication causing pneumonia. It has been shown that coexisting diseases like diabetes mellitus (DM), cardiovascular diseases (CVD), chronic lung diseases, ...etc have negative impacts on COVID-19 prognosis, causing an increased risk of developing severe complications such as acute respiratory distress syndrome (ARDS).4 The diagnosis of COVID-19 is established by detecting the virus in the clinical specimen by molecular assays.5 How- ever, other laboratory parameters are fundamental in evalu- ating the disease severity such as complete blood count (CBC), c-reactive protein (CRP), D-dimer, S. ferritin, lactate dehydro- genase (LDH), …etc.6 Current management strategies are not satisfactory enough to prevent the disease complications, particularly among patients with severe illnesses and comorbid diseases. Hence, it is essential to have an alternative measure to control the disease. The introduction of COVID-19 vaccine has revo- lutionized the disease magnitude. In Iraq, three COVID-19 vaccines were introduced to the community, namely: mRNA vaccine “Pfizer BioNTech”, the adenoviral vector vaccines ChAdOx1 nCoV-19 (AstraZeneca-Oxford), and Sinopharm (Beijing).7 Globally, Pfizer on December 24, 2020, AstraZeneca on January 28, 2021, and Sinopharm on September 10, 2021 were granted emergency use authorization by Food and Drug Administration (FDA).8 The first vaccine administered to the Iraqi population in March 2021 was Sinopharm.9 COVID-19 vaccines proved to be effective in preventing hospitalization.10 Fully vaccinated people might develop COVID-19 infection in an attenuated form. However, severe vaccine breakthrough infection is not uncommon, particu- larly among people with several months of vaccine adminis- tration as their immunity fades over time.11 To the best of our knowledge, there is little information regarding the prevalence and characteristics of hospitalized vaccinated COVID-19 patients in Iraq. Therefore, the objectives of this study were: first, to determine prevalence of vaccinated COVID-19 patients among hospitalized patients; second, to determine the mailto:paimanabdulsalam@yahoo.com 376 J Contemp Med Sci | Vol. 8, No. 6, November-December 2022: 375–381 Characterization of COVID-19 Hospitalized Adult Patients, Vaccinated vs Non-vaccinated in Duhok Province Original P.A. Mohammed et al. epidemiological, clinical, and laboratory characteristics of vaccinated and unvaccinated COVID-19 patients. Patients and Methods Setting The study was conducted in Duhok COVID-19 health facili- ties. First, Duhok COVID-19 hospital consisting of 50 ward beds and 20 ICU beds was mainly used for severe and critical cases. Second, a 100-bed hospital, called Lalav, primarily met patients with moderate to severe presentations. Study Design and Patients The study design was a prospective cross-sectional study on adult COVID-19 hospitalized patients. All PCR confirmed COVID-19 patients from October 1, 2021 until March 31, 2022 were enrolled. COVID-19 cases diagnosed based on other methods were excluded from the study. Clinico-demo- graphic, including vaccination status and laboratory parame- ters, was recorded in a standardized questionnaire. The study was approved by the Research Ethics Committee, Duhok Directorate General of Health on October 24, 2021 under ref- erence number: 24102021-10-10. Diagnosis and Measures COVID-19 hospitalized patients were classified for disease severity into mild, moderate, severe, and critical according to.12 Asymptomatic: Patients who test positive for SARS-CoV-2 via a virologic test (such as an antigen or nucleic acid amplifi- cation test [NAAT]), but who do not exhibit symptoms that are typical with COVID-19. Mild Illness: Patients who exhibits any of the COVID-19’s many symptoms (such as a fever, cough, sore throat, malaise, headache, muscle pain, nausea, vomiting, diarrhea, and a loss of taste and smell) but do not exhibit dyspnea, shortness of breath, or abnormal chest imaging. Moderate Illness: Patients with an oxygen saturation (SpO2) of less than 94% in ambient air at sea level and who exhibit signs of lower respiratory illness during clinical evaluation or imaging. Severe Type: Patients with a blood oxygen saturation (SpO2) of less than 94% on room air at sea level, a PaO2/FiO2 ratio less than 300 mm Hg, a respiratory rate greater than 30 breaths per minute, or lung infiltrates greater than 50%. Critical Type: Patients who develop respiratory failure, shock, and multiple organ dysfunction. The patients were grouped into the following categories according to Centers for Disease Control and Prevention (CDC), Morbidity and Mortality Weekly (MMWR) Report13 for vaccination status: 1. Unvaccinated: Individuals who are not vaccinated with any dose of COVID-19 vaccine or vaccine administration by 14 days or less. 2. Partially vaccinated: Individuals who were vacci- nated with the first dose for more than 14 days, or individuals who were vaccinated with two doses and have not reached 14 days post second vaccine. 3. Fully vaccinated: Individuals who were vaccinated with two doses with the second dose ≥14 days. All COVID-19 patients underwent laboratory testing including complete blood count (CBC), C-reactive protein (CRP), Lactate dehydrogenase (LDH), Serum ferritin, and D-dimer. Statistical Analyses The general information of the patients was presented in mean and Sta. deviation or number and percentage. The mortality rate and vaccination were determined in number and per- centage. Comparisons of general and medical information between vaccinated and unvaccinated individuals were exam- ined in an independent t-test and Pearson chi-squared test. Comparisons of biomedical measurements between vacci- nated and unvaccinated individuals were examined in an independent t-test. Comparisons of outcomes between vacci- nated and unvaccinated individuals, Association of vaccina- tion by symptoms among individuals, and symptoms by outcomes were examined in Pearson chi-squared tests. The significant level of difference was determined in a P-value of less than 0.05. The statistical calculations were performed in JMP pro 14.3.0. Results In total, there were 300 patients with a mean age of 60.73 years. There were 142 (47.33%) males and 158 (52.67%) females. Only 28 (9.33%) patients were vaccinated (Table 1). Table 2 presents the comparison of demographic, clinical, and laboratory parameters between vaccinated and unvacci- nated patients. In the vaccinated group, there were 17 (11.97%) Table 1. Demographic and clinical characteristics of the hospitalized patients Parameter (n = 300) Statistics No (%) 95% CI Lower CI to Upper CI Age (yrs.) 60.73 (15.83) 58.93–62.53 Sex Male Female 142 (47.33) 158 (52.67) 41.75–52.98 47.02–58.25 Vaccine status Unvaccinated Vaccinated 272 (90.67) 28 (9.33) 86.84–93.46 6.54–13.16 Type of vaccine Unvaccinated AstraZeneca Pfizer Sinopharm 272 (90.67) 7 (2.33) 15 (5.00) 6 (2.00) 86.84–93.46 1.13–4.74 3.05–8.08 0.92–4.29 Partially vaccinated (days) No Yes 295 (98.33) 5 (1.67) 96.16–99.29 0.71–3.84 Fully vaccinated (days) No Yes 277 (92.33) 23 (7.67) 88.76–94.84 5.16–11.24 Disease severity Moderate Severe Critical 11 (3.67) 221 (73.67) 68 (22.67) 2.06–6.45 68.41–78.33 18.29–27.73 The infection after first dose (days) was between 2 and 150 days infection after the second dose (days) was between 2 and 220 days. 377J Contemp Med Sci | Vol. 8, No. 6, November-December 2022: 375–381 P.A. Mohammed et al. Original Characterization of COVID-19 Hospitalized Adult Patients, Vaccinated vs Non-vaccinated in Duhok Province Table 2. Comparisons of general characteristics between vaccinated and unvaccinated patients General characteristics Vaccination status no (%) P-value (two-tailed)Unvaccinated (n = 272) (no/%) Vaccinated (n = 28) (no/%) Infection before vaccination No Yes Do not know 6 (21.43) 5 (17.86) 17 (60.71) Sex Male Female 125 (88.03) 147 (93.04) 17 (11.97) 11 (6.96) 0.1364a Age (year) 60.40 (16.19) 63.89 (11.55) 0.2676b Symptoms duration (days) mean (SD) 9.41 (3.09) 9.89 (2.62) 0.4273b Hospitalization duration (day) mean (SD) Range 11.14 (7.72) 1–77 days 8.17 (3.68) 1–60 days 0.0700b Hospitalization duration < one week 7–14 days 15–21 days 22–28 days > one month 83 (30.51) 81 (29.78) 46 (16.91) 24 (8.82) 38 (13.97) 9 (32.14) 12 (42.86) 3 (10.71) 1 (3.57) 3 (10.71) 0.5484a Disease severity Moderate Severe Critical 10 (3.68) 201 (73.90) 61 (22.43) 1 (3.57) 20 (71.43) 7 (25.00) 0.9532a Oxygen requirement No Yes 10 (3.68) 262 (96.32) 1 (3.57) 27 (96.43) 0.9775a CPAP requirement No Yes 178 (65.44) 94 (34.56) 21 (75.00) 7 (25.00) 0.3081a Invasive ventilation requirement No Yes 270 (99.26) 2 (0.74) 27 (96.43) 1 (3.57) 0.1509a Outcome of patients Died Recovered OR (95%): 1.29 (0.58–2.87) 148 (54.41) 124 (45.59) 17 (60.71) 11 (39.29) 0.5233a Biomedical measurements ALC LDH CRP D. Dimer 0.89 (0.43) 620 (148.40) 78.59 (57.99) 1305.58 (971.42) 0.98 (0.63) 429.5 (380.10) 68.14 (46.23) 1760.48 (1195.38) 0.3135b 0.2633b 0.4118b 0.0390b aPearson chi-squared test and bAn independent t-test. SD, Standard Deviation; OR, Odd Ratio; CPAP, Continuous positive airway pressure; SOB, Shortness of breath; ALC, Absolute Lymphocyte Count; LDH, Lactate Dehydrogenase; CRP, C-reactive protein. males and 11 (6.96%) females, while the unvaccinated group consisted of 125 (88.03%) males and 147 (93.04%) females. The mean age of unvaccinated patients was 60.4 and of vacci- nated patients was 63.89 years. The mean duration of symp- toms was 9.41 and 9.89 days of unvaccinated and vaccinated groups, respectively. Detailed information is demonstrated in Table 2. Figure 1 shows the patient outcome according to vac- cination status. The comparison of D-dimer level among vaccinated and unvaccinated patients showed a significant higher level of D-dimer among patients who received Sinopharm vaccine (Table 1, Figure 2). The most frequent sign and symptoms were SOB, fever, and cough as shown in Table 4. In term of frequency of vomiting and flu like symptoms between vaccinated subgroups and unvaccinated cases. Pfizer vaccine was significantly associated with vomiting (P = 0.0047) while Sinopharm vaccine was associated with flu like illness (P = 0.032). (Table 5). Regarding the comorbidities, CVD followed by DM were the most common risk factors associated with COVID-19 infection in both groups. Malignancy and smoking were signif- icant risk factors for COVID-19 infection in the unvaccinated group (Table 6). 378 J Contemp Med Sci | Vol. 8, No. 6, November-December 2022: 375–381 Characterization of COVID-19 Hospitalized Adult Patients, Vaccinated vs Non-vaccinated in Duhok Province Original P.A. Mohammed et al. Fig. 1 Comparisons of patient outcomes according to vaccination status in hospitalized patients. Fig. 2 Comparisons of D-dimer among patients with different types of COVID-19 vaccines. Table 3. D-dimer level among hospitalized patients according to the vaccination status AstraZeneca Pfizer Sinopharm Unvaccinated P-value D-Dimer 1631 (1085.58) 1684.42 (1246.27) 3030.17 (2598.60) 1305.58 (971.42) 0.0009 ANOVA one-way tests were performed for statistical analyses. Discussion COVID-19 vaccine has proven to be an important tool in con- trolling SARS-CoV-2 pandemic and in reducing disease severity among hospitalized patients. We investigated 300 hos- pitalized COVID-19 patients with a variety of demographic, clinical, and laboratory profiles. In the current study, the vac- cination coverage was 9.33%, which was low in comparison to studies from Iran,14 Turkey,15 Saudi Arabia,16 and India.17 On the contrary, only few studies reported a lower vaccination coverage for e.g. Peru (4.8%).18 This may be related to the lack of knowledge that COVID-19 vaccines prevent or attenuate diseases severity, concerns about the vaccination’s composi- tion, and side effects. Consequently, raising awareness con- cerning vaccine safety and uptake are highly mandatory. The most common administered vaccine in this study was Pfizer, which is in line to our previous study in evaluating COVID-19 vaccination program in Duhok.19 In the present study, the mean age of the hospitalized patients was 60.73 ± 15.83 yr, which was consistent with other studies.20 Generally, older adults are more prone to infections with a more severe course because of increasing incidences of coexisting comorbid dis- eases, hence a weakened immune system.21 In our study, the unvaccinated females were more infected, while vaccinated males had higher rates of hospital admissions. Ambrosino et al. in a review considered gender difference in COVID-19 patients, documenting a higher rate in males21 that was in contrast to our finding, which may be clarified by the study being limited to hospitalized patients and a small sample size. Whereas, the high rate of hospitalized vaccinated male patients could be linked to sex hormones, gender-related behavior, and differences in immunological function linked to the X chromosome.22 In our study, vaccinated patients had shorter hospital duration stays, which signifies the beneficial effect of COVID-19 vaccines. In agreement, several studies docu- mented this finding, indicating its efficacy in reducing burden on the healthcare system.23 In the current study, severe cases were predominated in both vaccinated and unvaccinated patients. This is justified according to our local COVID-19 management guidelines, as we admit only severe and critical cases to the hospitals.24 Hence, assessing COVID-19 vaccine effectiveness on the gen- eral population was unfit as only hospitalized patients were considered. However, though not statistically significant, the frequency of continuous positive airway pressure (CPAP) requirement was higher among unvaccinated group, which indicates the vaccine’s efficiency in reducing disease severity.25 Scanning laboratory variable, D dimer was significantly higher among vaccinated patients (P = 0.0390). Furthermore, comparing D-dimer among vaccine administered patients, Sinopharm was significantly associated with higher level (P = 0.0009). Our finding was in contrast to studies from Thailand26 and Turkey.27 The exact elucidation is dense at the moment; however, the higher D dimer level among Sinopharm patients might be related to patients having had received the vaccine at the beginning of COVID-19 vaccine campaign,7,28 having its effectiveness faded due to the long duration since patients acquired the infection. In this study, the mortality rate was relatively high among both vaccinated (60.71%) and unvaccinated (54.41%) patients. On contrary, other studies reported lower death rates.29,30 The high mortality rate in the current study is attributed first, to the admission of severe and critical cases in our hospitals while other studies included mild, moderate, and severe cases; second our study period was coincident majorly with the delta variant, hence worse prognosis of this variant, whereas other studies included other variants. Interestingly, we found that the incidence of vomiting and flu-like illness were higher among vaccinated than unvac- cinated patients. Vomiting and flu-like illness were signifi- cantly associated with Pfizer (P = 0.0047) and Sinopharm vaccines (P = 0.0328), respectively. There are reports about 379J Contemp Med Sci | Vol. 8, No. 6, November-December 2022: 375–381 P.A. Mohammed et al. Original Characterization of COVID-19 Hospitalized Adult Patients, Vaccinated vs Non-vaccinated in Duhok Province Table 4. Comparisons of symptomatology between vaccinated and unvaccinated patients Symptoms Vaccine status P-value Unvaccinated (n = 272) Vaccinated (n = 28) Number Percentage Number Percentage Fever 205 75.37 19 67.86 0.3843 Chill 59 21.69 5 17.86 0.6372 Rigor 32 11.76 2 7.14 0.4626 SOB 272 100.00 28 100.00 NA Cough 175 64.34 19 67.86 0.7107 Vomiting 32 11.76 8 28.57 0.0127 Chest pain 70 25.74 4 14.29 0.1808 Chest tightness 34 12.50 3 10.71 0.7844 Sore throat 39 14.34 3 10.71 0.5987 Voice change 27 9.93 2 7.14 0.6351 Loss of appetite 68 25.00 8 28.57 0.6791 Abdominal pain 14 5.15 1 3.57 0.7157 Flu-like illness 27 9.93 8 28.57 0.0034 Epigastric pain 42 15.44 3 10.71 0.5048 Constipation 45 16.54 5 17.86 0.8591 Headache 36 13.24 3 10.71 0.7057 Interscapular pain 28 10.29 1 3.57 0.2517 Nasal obstruction 18 6.62 0 0.00 0.1603 Loin pain 12 4.04 1 3.57 0.8353 General bodyache 55 20.22 5 17.86 0.7659 Fatigue 95 34.93 9 32.14 0.7682 Anosmia 26 9.56 3 10.71 0.4838 Parosmia 26 9.56 3 10.71 0.8438 Burning 10 3.68 1 3.57 0.9775 Ageusia 3 1.10 0 0.00 0.5765 Bitter taste 30 11.03 2 7.14 0.5258 Dry mouth 48 17.65 3 10.71 0.3524 Eye pain 18 6.62 1 3.57 0.5286 Sweating 36 13.24 4 14.29 0.8763 Nausea 20 7.35 4 14.29 0.1979 Backache 22 8.09 3 10.71 0.6321 Joints pain 34 12.50 4 14.29 0.7868 Diarrhea 25 9.19 1 3.57 0.3142 Table 5. Prevalence of vomiting and flu like symptoms with types of vaccinations Symptoms Type of vaccination no (%) P-value AstraZeneca Pfizer Sinopharm Unvaccinated Vomiting No Yes OR (95%CI) 7 (100) 0 (0.00) Infinity 9 (60.00) 6 (40.00) 0.2 (0.07-0.6) 4 (66.67) 2 (33.33) 0.27 (0.05-0.51) 240 (88.24) 32 (11.76) Reference 0.0047 Flu-like illness No Yes OR (95%CI) 5 (71.43) 2 (28.57) 0.28 (0.05-1.49) 11 (73.33) 4 (26.67) 0.3 (0.09-1.02) 4 (66.67) 2 (33.33) 0.22 (0.04-1.26) 245 (90.07) 27 (9.93) Reference 0.0328 Pearson chi-squared test was performed for statistical analyses. OR, Odd Ratio; CI, Confidence Interval. 380 J Contemp Med Sci | Vol. 8, No. 6, November-December 2022: 375–381 Characterization of COVID-19 Hospitalized Adult Patients, Vaccinated vs Non-vaccinated in Duhok Province Original P.A. Mohammed et al. Table 6. Association of comorbidities with vaccination status among hospitalized patients Risk factors Vaccine status P-value (two-sided) Unvaccinated (n = 272) Vaccinated (n = 28) Number Percentage Number Percentage DM 71 89.87 8 10.13 0.7776 CVD 149 90.85 15 9.15 0.9925 Preexisting lung disease 13 92.86 1 7.14 0.7729 Hookah 2 100.00 0 0.00 0.6489 Malignancy 7 70.00 3 30.00 0.0223 Obesity 22 100.00 0 0.00 0.1180 Immunosuppressive 8 100 0 0.0 0.4522 CKD 18 100.00 0 0.00 0.1603 Smoking 7 70.00 3 30.00 0.0223 Pregnancy 2 100.00 0 0.00 0.6489 Alcoholic 1 50 1 50 0.8824 Liver cirrhosis 3 100.00 0 0.00 0.5765 Pearson chi-squared tests were performed for statistical analsyes. DM, Diabetese Mellitus; CVD, Cardiovascular Disease; CKD, Chronic Kidney Disease. gastroparesis manifested as nausea and vomiting following Pfizer vaccine administration.31 The more frequent flu-like illness among Sinopharm receivers could be attributed to the faded effect of this vaccine among patients as explained ear- lier. Therefore, they were presented with this illness as a fre- quent symptom of COVID-19. In the present study, considering comorbidities, smoking and malignancy were significant risk factors for COVID-19 infection in unvaccinated patients. Smoking increases risk for acute respiratory infection in general, and increases entry of SARS-CoV-2 to host by upregulation of the angiotensin con- verting enzyme 2 (ACE2) receptor in particular.32 Whereas, malignancy in addition to chemotherapy regimens can weaken immune cells and create immunosuppressive state to patients, hence increase susceptibility to the infection.33 The study had several limitations, first, the study period was limited to a few months, and accordingly this could be a barrier for evaluating the true prevalence of the circulating strain. Second, the study depended on the outbreak magni- tude, so the disease declining incidence often had an impact on sample size. Conclusion The SARS-CoV-2 pandemic can be controlled with the use of the COVID-19 vaccine, which has also been shown to lessen the severity of illness in hospitalized patients, we looked at 300 COVID-19 patients who were hospitalized and had dif- ferent demographic, clinical, and laboratory profiles. In this study the majority of population were unvaccinated. Among those who had received vaccinations, Pfizer was most popular. The majority of cases were old ages. The unvaccinated females were more infected, while vaccinated males had higher rates of hospital admissions. The unvaccinated group had longer dura- tion in hospital stay. About three quarter of study population were severe cases. D dimer was significantly higher among vaccinated patients (P = 0.0390). According to the data, the mortality rate was relatively high among both groups. Regarding the clinical characteristics, vomiting and flu-like illness showed higher prevalence in vaccinated patients with significant difference. In terms of comorbidities, smoking and malignancy were significant risk factors for COVID-19 infec- tion in unvaccinated patients. The presence of a COVID-19 vaccine and the proper implementation of a worldwide vacci- nation campaign are essential in the fight against a public health emergency like a COVID-19 pandemic. Abbreviations WHO: World Health Organization, COVID-19: Coronavirus Disease 2019, SARS CoV 2: severe acute respiratory syndrome coronavirus 2, DM: diabetes mellitus, CVD: cardiovascular diseases, ARDS: acute respiratory distress syndrome, CBC: complete blood count, CRP: c-reactive protein, LDH: lactate dehydrogenase, mRNA: Messenger Ribonucleic acid, FDA: Food and Drug Administration, PCR: Polymerase Chain Reaction, NAAT: nucleic acid amplification test, SpO2: Satura- tion of Peripheral Oxygen, PaO2/FiO2: Partial pressure of oxygen in arterial blood /Fraction of Inspired Oxygen, CDC: Centers for Disease Control and Prevention, MMWR: Mor- bidity and Mortality Weekly, CI: Confidence Interval, SD: Standard Deviation, OR: Odd Ratio, SOB: Shortness of breath, CKD: Chronic kidney disease, US: United States, MoH: Min- istry of Health, CPAP: Continuous positive airway pressure, ACE2: angiotensin converting enzyme 2. Acknowledgments Special thanks to all the doctors and laboratory personnel at Duhok COVID-19 and Lalav Hospitals, who assisted me in completing data collection. Conflict of Interest The authors affirm that they do not have any conflict of interests.  381J Contemp Med Sci | Vol. 8, No. 6, November-December 2022: 375–381 P.A. Mohammed et al. Original Characterization of COVID-19 Hospitalized Adult Patients, Vaccinated vs Non-vaccinated in Duhok Province References 1. García-Basteiro AL, Chaccour C, Guinovart C, Llupià A, Brew J, Trilla A, et al. Monitoring the COVID-19 epidemic in the context of widespread local transmission. The Lancet Respiratory Medicine. 2020;8(5):440–2. doi: 10.1016/s2213-2600(20)30162-4. https://pubmed.ncbi.nlm.nih. gov/32247325/ 2. Lotfi M, Hamblin MR, Rezaei N. COVID-19: Transmission, prevention, and potential therapeutic opportunities. 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