Table 1.
ID | First author (reference) | Type of study | Publication year | country | Study population | age | Gender | Sampling method | Viral load and its association with disease severity | Sign/symptom | Comorbidities | Lab test | Clinical outcome | Transmission | Important finding |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Aoki et al. 26 | Cross‐sectional | 2021 | Japan | 24 | N/A | Female/male | RT‐PCR | There was a high correlation between viral load calculated using the RT‐PCR cycle threshold value and antigen concentration. The tendency to decrease antigen concentration over time after disease onset is associated with viral load. C t value: 25 | N/A | N/A | N/A | N/A | N/A | SQT is fully compatible with RT‐PCR and should be useful in diagnosing COVID‐19 in any clinical setting |
Nasopharyngeal swab | |||||||||||||||
2 | Aydin et al. 27 | Case series | 2021 | Turkey | 125 | 62,1 | 48.8% male | RT‐PCR | The effect of SARS‐CoV‐2 viral load on saliva and other substances was not found in their prognosis. C t value: 22.28 | N/A | Hypertension, COPD, DM, malignancy, immune deficiency, cardiovascular disease, and asthma | N/A | N/A | N/A | The viral load of saliva in the early stages of COVID‐19 infection may have a high prognostic value in predicting disease progression in patients over 45 years of age. Saliva is a good substance in COVID‐19 screening |
Oronasopharyngeal (ONP) samples and saliva samples | |||||||||||||||
3 | Berastegui‐Cabrera et al. 28 | Cross‐sectional | 2021 | Spain | 72 | 66 | 56% male | RT‐PCR | No association was found between viral load in NP samples and the presence of SARS‐CoV‐2 RNAemia. The absence of differences in NP viral load between patients with SARS‐CoV‐2 RNAemia and without it proves that the clinical development index of COVID‐19 patients is better than that of NP viral load. The median viral load in NP swabs = 6.98 log10 copies/ml (IQR, 5.15–8.20) | Arthromyalgias, coryza, cough, dyspnea, headache, odynophagia, diarrhea, anosmia, weakness, and dysgeusia | Chronic kidney disease, solid‐organ transplantation, connective tissue disease, and chronic liver disease | Leukocytes: 5.22, 7.00, Neutrophils: 3.49, 4.79, Lymphocytes: 0.58, 1.36, Platelets: 158, 248, Hemoglobin: 13, 13.8, AST: 37, 26, ALT: 33, 23, Bilirubin: 0.59, 0.46, Sodium: 2, 4, Potassium: 2,1, Creatinine: 4, 6, C‐reactive protein: 97.9, 44.9, Ferritin: 625.6, 442, D‐dimers: 1430, 620, LDH: 450, 251.5, | ARDS, multiple organ failure, IMV, ICU admission, mortality | N/A | The presence of RNAemia SARS‐CoV‐2, in the first emergency assessment, is more common in patients with severe chronic underlying disease, such as chronic liver disease and solid organ transplantation, with viral load in the upper respiratory tract and with adverse outcomes |
Nasopharyngeal swabs | |||||||||||||||
4 | Buetti et al. 29 | Cross‐sectional | 2021 | Switzerland | 90 | 62.5 | 78.9% male | RT‐PCR Nasopharyngeal swab | Viral load (log10 copies/ml), median [IQR]: 3.3 [1.8; 5.2] That viral load in the LRT was associated with the 6‐week mortality | Cardiovascular, Immunosuppression, DM, Renal failure, Cancer, and Chronic respiratory failure | N/A | N/A | N/A | Delay in LRT virus averaged approximately 30 days in critically ill patients, and viral load in LRT was associated with 6‐week mortality | |
5 | Buder et al. 30 | Cohort | 2021 | Germany | 59 | Median: 48 years | 49% | Quantitative real‐time PCR of respiratory samples | Median viral load (IQR): 6.80 × 104 (4.75 × 103–1.81 × 106) RNA copies/ml | N/A | 10 patients had immunosuppression | N/A | 34 outpatient, 20 admitted to ICU | Higher viral load correlated with a higher chance of viral transmission | SARS‐CoV‐2 infectivity correlated with viral load, with the best predictor of infectivity being viral loads above 1.0 × 107 RNA copies/ml. The probability of virus isolation from respiratory samples also correlated positively with viral load. Seroconversion terminated SARS‐CoV‐2 infectivity |
6 | Cho et al. 31 | Pospective observational | 2020 | China | 75 | 36.4 ± 16.3 | 48% male | RT‐PCR Nasopharyngeal and deep throat swabs | There was no correlation between the recovery time of olfactory or gustatory disorders and the Ct value of PCR was sampled indirectly from nasopharyngeal swabs and deep throat reflected the viral load of SARS‐CoV‐2. C t value: 28.3 ± 6.7 | Rhinorrhea, Purulent nasal discharge, Taste change, Nasal blockage, Epistaxis, Cough, Fever, Dyspnea, and smell change. | N/A | N/A | N/A | N/A | There is no association between severity and improvement of olfactory and taste disorders with SARS‐CoV‐2 viral load |
7 | Chua et al. 32 | Cross‐sectional | 2021 | China | 91 | Asymptomatic Male:8.6 (4.3–11.0), Symptomatic Mean (IQR): 9.2 (4.0–15.0) | Asymptomatic 57.1% male, Symptomatic 44.4% male | RT‐PCR Nasopharyngeal swab (NPS), and saliva samples collected on admission | The onset days of symptoms for all patients were inversely related to the NPS and saliva viral loads. Viral load (log10 copies/ml): lymphopenia (NPS, Saliva): 6.7, 5.8 viral load (log10 copies/ml):: nonlymphopenia (NPS, Saliva): 6.2, 4.9 | N/A | Total white cell count (×109/L): 6, 5.8‐Hemoglobin (g/dl): 12.8, 13.2‐Platelets (×109/L): 258.4, 278.1‐Urea (mmol/L): 3.4, 3.9‐Creatinine (µmol/L): 41.6, 44.9‐Creatine Kinase (U/L):122.5, 99.7‐Troponin I (ng/l): 1.9, 11.3‐C Reactive Protein (mg/dl): 1.4, 1.7‐Erythrocyte Sedimentation Rate (mm/h):8.6, 12‐ | N/A | N/A | Salivary viral loads in hospitalized children with clinical and immune profiles are better than NPS | |
8 | de la Calle et al. 33 | Cross‐sectional | 2021 | Spain | 455 | 64.9 ± 18.1 | 56% male | rRT‐PCR nasopharyngeal | Patients with respiratory failure had a higher viral load at admission than those who did not. Low viral load (C t > 30), Intermediate viral load (C t 25–30): 1.81, high viral load (C t < 25): 2.99 | Fever, Vomiting, Cough, Tachypnea, Diarrhea, SpO2 < 90% air room, Myalgia and Dyspnea | Cardiovascular disease, chronic renal disease, chronic lung disease, DM, immunosuppression, obesity, current or former smoker, and chronic liver disease | LDH (U/L): 326.6, GOT (U/L): 32, GPT (U/L): 25, CPK (U/L): 86, TnT (U/L): 10.5, C‐reactive protein (mg/dl): 7.7, Ferritin (mg/dl): 699, D‐dimers (ng/ml): 664 | Need for supplemental oxygen, ARDS, noninvasive mechanical ventilation, ICU admission, Septic shock, Prone position, MACE event, Acute kidney injury (AKI), Venous thrombosis, Hepatitis, Respiratory failure, Invasive mechanical ventilation, and mortality | N/A | The SARS‐CoV‐2 viral load, measured by Ct value of rRT‐PCR in pharyngeal swabs at admission, is a good indicator of the prognosis for respiratory failure |
9 | He et al. 34 | Cohort | 2020 | China | 23 | 41 | 43.5% males | qRT‐PCR Pharyngeal swab | Minimum viral load: 40 C t. Asymptomatic type patients had lower viral loads than common and severe types | Fever, cough, nasal congestion, dizziness, fatigue, arthralgia, | human endogenous retrovirus‐H (Hervs) and Human picobirnavirus (HPBV) | Patients with severe disease had more abnormal laboratory test results (including leukopenia and lymphocytopenia) | no significant correlation was observed between age and Ct value also no association between Ct value and severity of illness was observed. Significant positive relation has been detected between peak viral load and severity of illness. | Weaker transmission capacity of asymptomatic cases due to the lower viral load | Asymptomatic type patients had lower viral loads than common and severe types |
10 | Jacot et al. 35 | Cross‐sectional | 2020 | Switzerland | N/A | 0‐99 years | Female/male | RT‐PCR Nasopharyngeal swab | Range: 3–10 log copies/ml. Median: 6.78 log10 copies/ml In the first period of covid‐19 outbreak viral load was higher SARS‐CoV‐2 viral load seem to be a substandard predictor of disease outcome, COVID‐19 disease severity is not significantly related to viral replication in the upper and lower respiratory tracts | Fever cough | N/A | N/A | In the first period of covid‐19 outbreak viral load was higher | below 1000 copies/ml values can be considered at slight risk of transmission | Despite there are significant differences between viral loads of different viruses, SARS‐Cov‐2 had a alike viral load to Respiratory syncytial virus and influenza B than other coronaviruses |
11 | Jain et al. 36 | Comparative | 2021 | India | 200 | group A 35.23 ± 11.99, group B 35.32 ± 12.92 | 60% male | RT‐PCR Nasopharyngeal swab | Group A with olfactory and taste dysfunction: 24.43 C t. Group B without OTD: 27.39 C t. The patients with taste and olfactoryimpairment at diagnosis had more viral load than patients without taste and olfactoryimpairment | Loss of smell and taste malaise sore throat cough fever nasal discharge | N/A | RT‐PCR was utilized to test The COVID‐19, with 3 gene detection: RdRp (RNA‐dependent RNA polymerase), E (Envelope encoding) gene, and N (Nucleocapsid encoding) gene. For analysis cycle threshold was utilized. | N/A | N/A | The patients with OTD at diagnosis had more viral load than patients without OTD |
12 | Kam et al. 37 | Cohort | 2021 | Singapore | 17 | 7.7 | Female/male | RT‐PCR Nasopharyngeal swab | Symptomatic: 28.6 C t. Asymptomatic: 36.7 C t higher viral loads was seen in symptomatic children in comparison to asymptomatic children | Upper respiratory tract symptoms with mild sickness signs | N/A | N/A | patients with mild and severe chest CT involvement had significantly lower viral load in comparison to patients with no chest CT lesions. | symptomatic children in had high viral load in the first stage of sickness indicates the transmission potential of presymptomatic children. | Children with symptomshad higher viral loads than children without symptoms |
13 | Karahasan Yagci et al. 38 | Cohort | 2020 | turkey | 730 | 35 | 49.9% female | RT‐qPCR Nasopharyngeal swab | Without CT scan involvement: 24.9 mild CT involvement: 27.8 moderate CT involvement: 29.4 severe CT involvement: 27.9. The oppositecorrelation of chest CT Total severity score (TSS) and viral load was seen. Significantly higher viral loads was observed in patients with no chest CT lesions in comparison to patients with mild and severe chest CT involvement | Fever, cough and dyspnea | Hypertension, diabetes mellitus, cardiovascular disease, chronic obstructive pulmonary diseases (COPD), cancers, HIV, collagenosis, and chronic liver disease | N/A | 284 (39%) patients were admitted to hospital and 27 of patientsexpired during the hospitalization. | N/A | The oppositecorrelation of chest CT total severity score (TSS) and viral load |
14 | Kawasuji et al. 39 | Case‐control | 2020 | Japan | 28 | Median age: 45.5 years | 53.6% male | rRT‐PCR Nasopharyngeal swab | 33.6 ± 5.5 C t. A significant viral load and recovery time differencewas observed between patients with pulmonary involvement and patients without pulmonary involvement | N/A | N/A | N/A | Significantly higher viral load at the beginning of sampling in symptomatic patients than in asymptomatic patients was observed. Also, Children had significantly higher viral load than adults in the beginning of sampling. | A high nasopharyngeal viral load can be connected to the secondary transmission of COVID‐19 | Secondary transmission of COVID‐19 can be related to high nasopharyngeal viral load. Additionally, the viral load can help describe why transmission is observed in some patients, but not in others, particularly among patients who live in same house |
15 | Kim et al. 40 | Retrospective | 2021 | South Korea | 106 | Mean age: 28.0 ± 9.3 years | 43.4% male | RT‐PCR Nasopharyngeal/oropharyngeal swab | 33.6 ± 5.5 C t. Viral load and recovery time were significantly different between pulmonary involvement patients and patients without pulmonary involvement was observed | Cough, fever, headache, hyposmia, rhinorrhea, sputum, muscle pain, diarrhea, chest pain, ocular pain | Rhinitis, asthma, migraine, iron deficiency, anemia, hyperlipidemia, endometriosis, depression disorder, hair loss, atopic dermatitis | N/A | Recovery times were significantly slower in the patients with pulmonary involvement than patients without involvement. | N/A | Viral load and recovery time were significantly different between pulmonary involvement patients and patients without pulmonary involvement was observed. The cycle threshold cutoff value for the existence of pneumonia was 31.38 |
16 | Kociolek et al. 41 | Retrospective | 2020 | USA | 817 | 0‐17 years | 52.1% male | RT‐PCR Nasopharyngeal swab | Asymptomatic children: 2.0 × 103 copies/ml symptomatic children: 1.3 × 107 copies/ml. In children without symptoms lower viral load was found in their nasopharynx/oropharynx than children with symptoms | Cough, fever/chills, dyspnea, pharyngitis, loss of taste or smell, headache, abdominal pain, diarrhea, fatigue, myalgias, congestion/rhinorrhea, nausea/vomiting, rash, or conjunctivitis | Immunocompromised = 51. Diabetes = 19 | N/A | Ct values were significantly higher in children without symptoms than children with symptoms. Also, significantly lower viral loads was observed in asymptomatic than symptomatic children. | N/A | Asymptomatic children had low viral loads in their nasopharynx/oropharynx than children with symptoms |
17 | Kriegova et al. 42 | Prospective | 2021 | Czech Republic | 1038 | 50.0 ± 3.3 | Female/male | RT‐PCR Nasopharyngeal swab | Asymptomatic and mild group 23.65 (±7.62) C t. Moderate group 27.68 (±6.98) C t. Severe and critical group 26.52 (±4.82) C t. High levels of virus in the respiratory tract and excessive producing of chemokines and cytokines between first 2 weeks from the onset of symptoms were significantly related to severity of the COVID‐19 | N/A | N/A | N/A | self‐conductnasal‐swab in combination with direct RT‐qPCRare easy, low‐cost and quick CoV‐2 testing method which could significantly increase the extent of the teststrategies which are needed to control the expansion of COV‐19 during and post‐pandemic era | N/A | High levels of virus in the respiratory tract and too much productionof chemokines and cytokines and between the first two weeks from the onset of symptoms were significantly related to severity of the COVID‐19 |
18 | Kwon et al. 43 | Prospective | 2020 | South Korea | 31 | 32‐72 years | 58% female | Nasopharyngeal swab RT‐PCR | Initial viral load at five toten days from onset of symptoms in the asymptomatic and mild group, moderate group, and the severe and critical group was 32.65 (±7.62), 27.68 (±6.98), and 26.52 (±4.82) cycles | Fever, chill, cough, sputum, sore throat, dyspnea, rhinorrhea chest pain, headache, myalgia, nasal congestion, hyposmia, hypogeusia, pneumonia | Diabetes mellitus, hypertension, chronic lung disease, chronic liver disease, obesity (body mass index > 25), smoking | Old age, initial low WBC count, low platelet count, high CRP level, and fever were identified as factors associated with severity | Early increases in type I IFN response might be involved in the pathophysiology of severe COVID‐19 by eliciting subsequent excessive responses of multiple cytokines and chemokines | N/A | Higher viral load, stronger antibody response, and excessive inflammation at first two weeks from onset of symptoms are related to the COVID‐19 severity |
19 | Le Borgne et al. 44 | Retrospective | 2021 | France | 287 | 50.0 to 73.0, median age: 63.1 | 65.8% male | Pharyngeal swabs qRT‐PCR | 4.76 (3.29–6.06) log10 copies/reaction Nasopharyngeal viral load measured by RT‐PCR during beginning emergency department (ED) viral load is not predictor of severity and mortality in COVID‐19 patients | N/A | Hypertension, cardiovascular disease, diabetes mellitus, renal insufficiency, dialysis, COPD, malignancies, immunotherapy, corticosteroids | At emergency department admission, patients who didn't survive in comparison to survived patients. had significantly higher C‐reactive protein (122 vs. 74 mg/L, p = .007) and creatinine (p = .036). Nonsurvivors were also more likely to present with anemia (p = .003) and lymphopenia (p = .02) than survivors | Forty‐two patients (14.6%) died. | Nasopharyngeal viral load was measured by RT‐PCR at emergency department admission viral load isn't predictor of severity and mortality in COVID‐19 patients | |
20 | Piubelli et al. 45 | Cross‐sectional | 2021 | Italy | 273 | N/A | Female/male | RT‐PCR Nasal and Pharyngeal swabs | Viral load decreased during 2 months of quarantine (C t decreased from 24 to 34). Alongside, the number of patients who need intensive care significantly decreased because of the reduction of viral load | N/A | N/A | More probable in high‐transmission setting compared with low‐transmission setting | ICU admission (5.3%) | N/A | N/A |
21 | Rauch et al. 46 | Cohort | 2021 | USA | 1808 | 27.3 ± 11 | 53% male | RT‐qPCR and CRISPR‐based assay Nasopharyngeal swab | Viral load = 286–510,000 copies/μl. The shift of viral load is shown in those who stayed at home | Nasal congestion, sore throat, fatigue, anosmia | N/A | 8 positive participants by CRISPR‐based assay and 9 by RT‐qPCR were detected | All were alive at the end of the study | N/A | The prevalence of SARS‐CoV‐2 in cohort 2 was changed and it was because of decreased community restrictions and increased social interactions |
22 | Sarkar et al. 47 | Cross‐sectional | 2020 | India | 138 | N/A | Female/male | RT‐PCR Nasopharynx swab (NPS) and oropharynx swab (OPS) | In those with C t values between 17 and 23, patients had severe infections | N/A | N/A | N/A | N/A | In high viral load cases, the rate of transmission was 8‐times more than low viral load cases. Patients with Ct above 33‐34 were not contagious | In individuals with high viral load, the possibility of transmission was almost 8 times higher compared to low viral load individuals. Of those who were infected, 7% had a high viral load, 9% moderate viral load, and 84% low viral load based on Ct values. The probability of transmission in those with high viral load was 6.25 in comparison with law viral load with 0.8 |
23 | Shlomai et al. 48 | Cross‐sectional descriptive | 2020 | Israel | 170 | 62 | 58% Male | Nasopharyngeal samples RT‐PCR | Viral load was significantly higherin ventilated and nonsurvivors patients (eightfold more than other patients). Low viral load was associated with decreased risk of mortality and intensive care | Hypoxemia | N/A | N/A | 21 death | N/A | Viral load was directly linked to hypoxemia. Viral load was significantly related toblood oxygen saturation. The patient's age significantly correlated with viral load |
24 | Shrestha et al. 49 | Cohort | 2020 | USA | 230 health care personnel (HCP) | N/A | Male 36% | PCR Nasopharyngeal swab | Viral load in 2 or 3 days after onset of symptoms was the peak. Time since onset of symptoms was significantly related to viral load | N/A | Chronic lung disease, current smoker, chronic heart disease, hypertension, liver cirrhosis, immunocompromised, diabetes mellitus, chronic kidney disease | N/A | N/A | N/A | 86.5% of transmission potential was in the first 5 days since onset of symptoms |
25 | Singanayagam et al. 50 | Cross‐sectional | 2020 | England | 754 samples from 425 symptomatic cases | 0‐100 years old | Female/male | RT‐PCR Nose, throat, combined nose‐and‐throat and nasopharyngeal swabs | There was no difference in C t value between asymptomatic (C t = 31.23), mild to moderate (C t = 30.94), and severe cases (C t = 32.55). In the first week of onset of symptoms, viral load was higher than the second week | N/A | N/A | In 42% of cases, culture was positive. The culture positivity during the first week of infection was significantly higher than the second week | N/A | N/A | Cases in the 81–100 year age group were more asymptomatic than other groups |
26 | Soria et al. 51 | Cohort | 2020 | Spain | 448 | 71.04 ± 18.29 | 45.7% male | RT‐PCR Nasopharyngeal swabs | Mean C t: mild (35.75 ± 0.45), moderate (32.69 ± 0.37), severe (29.58 ± 0.70). Viral load is a predictor of disease severity. High virus loading worsens the prognosis of the disease. C t value was significantly law in the severe group in comparison with the moderate and mild group | N/A | Hypertension, cardiovascular disease, diabetes. Obesity, asthma, COPD | N/A | Cases of the severe group include 23% of total cases and all of them were admitted. Also, 18.3% died during 90 days after diagnosis, 75 cases in the severe group, three cases in moderate, and four in the mild group | N/A | N/A |
27 | To et al. 52 | Cohort | 2020 | China | 23 | 62 | 56.5% male | RT‐qPCR Oropharyngeal saliva samples | The median viral load was 5 × 2 log10 copies/ml. The first week after the onset of symptoms, the viral load is high but decreases over time | Fever (96%), cough (22%), chills (17%), dyspnea (17%), runny and blocked nose, sore throat, chest discomfort, nausea, diarrhea, myalgia, malaise. In 15 (65%) CXR abnormalities were seen. In 17 (74%) multifocal ground‐glass lung opacities were seen | 48% had clinical medical illnesses including hypertension and diabetes | Those patients who had comorbidities had a lower anti‐RBD IgG OD compared to those without comorbidities | Five patients were admitted to ICU, two of them required intubation, and also two of them died | N/A | Older age was associated with a higher viral load. The antibody response occurred 10 days or later since the onset of symptoms |
28 | To et al. 53 | Cross‐sectional | 2020 | China | 12 | 62.5 | 58% male | RT‐qPCR Nasopharyngeal or sputum specimen | The median viral load was 3.3 × 106 copies/ml. On the first day of hospitalization viral load was slightly higher than other days. After day 11 viral load started to shed till being undetectable | N/A | N/A | According to viral culture, saliva contains live viruses and potentially can transmit the virus | At the end of the survey, all patients were alive | N/A | Saliva can be obtained from the patient without invasive procedure and it leads to reduce in nosocomial transmission of the virus |
29 | Trunfio et al. 54 | Retrospective cross‐sectional | 2021 | Italy | 200 | 56 | 58% male | RT‐PCR Nasopharyngeal swab | Viral load was associated with the severity of the disease | Gastrointestinal, neurological, respiratory, and systemic involvement, headache, olfactory and gustatory dysfunction, nausea and vomiting, diarrhea, fever, arthralgia, asthenia and malaise, cough, dyspnea, pharyngitis, and runny nose | Participants of group A (C t ≤ 20) had at least one comorbidity that was significantly different from the other two groups. Hypertension, COPD, asthma, obesity, active smoking, diabetes, cancer | N/A | 36.5% of cases were isolated at home and 63.5% were admitted to the hospital. Of those admitted, 16% died (including 20 cases in group A, 7 cases in group B, 5 cases in group c). 5% of all cases required intubation | N/A | Group A (C t ≤ 20) washospitalized more than group C (C t > 28). COVID‐19 severity and worse outcomes were significantly higher in group A compared with the other two groups (B: 20 < C t < 28). There was no association between viral load and prevalence of olfactory/taste disorder |
30 | Tsukagoshi et al. 55 | Cross‐sectional | 2021 | Japan | 286 | 39 ± 35 | 56.3% male | RT‐qPCR Nasopharyngeal swab | In fatal cases 3.57 × 109 ± 4.70 × 109 copies/ml; in survived cases 3.92 × 108 ± 1.60 × 109 copies/ml; in asymptomatic 4.92 × 107 ± 1.48 × 107 copies/ml. In fatal cases, viral load was significantly higher than symptomatic and asymptomatic cases. Poor prognosis in elderly patients was predicted in those with a high viral load | Fever, sore throat, cough | N/A | N/A | 5.2% of cases died | N/A | Pneumonia was more common in patients who died than in those who survived |
31 | Wang et al. 56 | Cross‐sectional | 2020 | China | 23 | 56 | 82.6% male | RT‐PCR Nasal swab, pharyngeal swab, sputum | In severe cases in comparison with mild cases, the viral load peak was significantly higher | N/A | N/A | N/A | 43.5% of cases admitted to ICU | N/A | N/A |
32 | Faíco‐Filho et al. 57 | Cohort | 2020 | Brazil | 875 | 48 | 49.1% male | RT‐PCR Nasal swab | Samples with C t values <40 were considered positive. Survivors presented a significantly higher initial C t value than that of nonsurvivors Mortality rates were 46% among patients with a high viral load (C t < 25) and 22% among patients with a low viral load | N/A | N/A | The higher the viral load, the worse the disease and the poorer the consequences | N/A | the Ct value could be used as a tool to help with the identification of patients at a higher risk for severe consequences | |
33 | Guo et al. 58 | Cohort | 2020 | china | 195 | 49.24 ± 15.99 | 48.2% males | RT‐PCR Nasopharyngeal swab | More severe patients seem to have a higher initial viral load. a significant increasing trend of initial viral load versus illness severity | Higher maximum body temperature within 24 h after hospitalization anddurationoffever (days) correlation with severe disease | Hypertension, Diabetes mellitus, Cardiovascular disease, Cerebrovascular disease, Chronic kidney disease | Higher plasma C‐reactive protein (CRP), D‐dimer, procalcitonin (PCT), and aspartate aminotransferase (AST); larger count of white blood cells (WBC) and neutrophil (NE), but relatively reduced lymphocyte count. A higher NE to lymphocyte ratio (NLR) was seen at a severe disease | N/A | N/A | Age, fever, peak body the temperature in 24 h after hospitalization, CRP, WBC, NE, NLR, AST, D‐Dimer, and PCT are positively correlated with severity, Patients with higher upper respiratory tract viral load at admission are more likely to develop severe symptoms and may need more aggressive treatment |
34 | Hasanoglu et al. 59 | Retrospective study | 2020 | Turkey | 60 | 33.9 | 48% males | RT‐PCR Saliva, urine, blood, and anal swab samples | The viral load of standards synthetic SARS‐CoV‐2 RdRp fragment/ml was between 2.5 × 102–5 copy/ml. No significant difference in the probability of PCR positivity across symptomatic and asymptomatic patients was found. PCR positivity does not always indicate infectivity | Cough and fatigue were the most observed symptoms on admission, 51.7%, and 30.5%, respectively | At least one comorbidity was present in 8 (13.3%) patients | N/A | Factors associated with poor prognosis are found to be significantly correlated with low viral load | N/A | A significant decrease in viral load of nasopharyngeal/oropharyngeal samples was observed with increasing disease severity |
Abbreviations: LRT, lower respiratory tract; NPS: nasopharyngeal swab.