Association of SARS-CoV-2 cycle threshold (Ct) values with clinical course and serum biomarkers in COVID-19 patients.

INTRODUCTION: Our knowledge has gaps regarding severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication levels and its association to severity of Coronavirus disease 2019 (COVID-19). The aim of this study was to investigate the association of SARS-CoV-2 viral load with disease severity and serum biomarkers in COVID-19 patients. METHODOLOGY: Viral load was determined via cycle threshold (Ct) values of SARS-CoV-2 real-time reverse transcriptase-polymerase chain reaction (RT-PCR) in 214 adult patients. Ct values were compared with clinical severity, biochemical and hematological biomarkers. RESULTS: Clinical course of the disease was mild (49.1%), moderate (40.2%), and severe (10.7%). Median Ct value was 28.2 (IQR: 22.2-33.8) during the first week of the disease. Ct values were lower within five days after symptom onset [lowest Ct value on the third day (median: 24, IQR: 20.6-32.3)], but they increased significantly during the second and third weeks. No association was detected between admission Ct values and disease severity. Gender, age, co-morbidity, and mortality did not differ significantly in patients with low (≤ 25) and high (> 25) Ct values. White blood cell, neutrophil, platelet, and especially lymphocyte counts, were significantly lower in patients with low Ct values. CONCLUSIONS: No definitive/clear correlation between SARS-CoV-2 viral load and severity and mortality was found in the studied COVID-19 patients. However, neutrophil, platelet, and especially lymphocyte count were significantly lower in patients with a high viral load.

Changing epidemiology of influenza and other respiratory viruses in the first year of COVID-19 pandemic.

INTRODUCTION: We aimed to determine the epidemiological change in influenza and other respiratory tract viruses isolated from patients with nasopharyngeal swab samples in our hospital during the COVID-19 period. METHODS: We investigated nasopharyngeal swabs for respiratory viruses between March 2020 and February 2021 during the first year of pandemic in Turkey. We used QIAStat Dx Respiratory panel (Qiagen, Germany) in QIAStat Dx (Qiagen, Germany) for detection of respiratory viruses between March 2020 and February 2021. Respiratory panel kit included influenza A, B, influenza A H1N1, rhinovirus/enterovirus, parainfluenza (PIV) 1,2,3,4, coronaviruses (CoVs) NL 63, 229E, OC43 and HKU1, human metapneumovirus (MPV) A/B, bocavirus, respiratory syncytial virus (RSV) A/B and adenovirus. RESULTS: We retrospectively analyzed the results of 319 nasopharyngeal swab samples. The average age of 199 (62.4%) male and 120 (37.6%) female patients between the ages of 0-92 was 16 years. We found that 101 (31.7%) samples were positive for viruses. Rhino/enteroviruses were the most common viruses in all age groups. Influenza positivity rate during the first year of pandemic declined to 2.3% from 17.3% among the previous year. MPV infection activity did not change during the pandemic. DISCUSSION: According to our findings we argue that epidemiology of respiratory viruses has changed during the pandemic period. Despite the current clinical focus on the COVID-19 pandemic, clinicians should keep in mind that rhino/enterovirus and MPV infections may mimic COVID-19 and respiratory infections should be differentially diagnosed with rapid multiplex kits containing SARS-CoV-2, rhino/enterovirus and MPV.