A high viral load is a predictor of disease progression in patients with COVID-19 who were admitted with pneumonia. Photo credit: American Thoracic Society
A new study, published online in the Annals of the American Thoracic Society, looked at whether the amount of RNA or genomic load of SARS-CoV-2 detected in swab tests of patients hospitalized with viral pneumonia associated with a more severe COVID -19. SARS-CoV-2 is the virus that causes COVID-19. Previous studies on this issue have had conflicting results.
Ioannis M. Zacharioudakis, MD, Infectious Disease Specialist in the Department of Medicine, New York University’s Grossman School of Medicine, and co-authors reviewed “Association of SARS-CoV-2 Genomic Exposure to COVID-19 Patient Outcomes.” The medical records of 314 patients who came to the emergency room at NYU Langone Health between March 31 and April 10, 2020 and who were diagnosed with COVID-19 on a molecular diagnostic test (RT-PCR) and who also had viral pneumonia was severe enough to require hospitalization. This study was conducted as a retrospective cohort study – a study that follows former patients with common characteristics.
“We have shown that in patients admitted to hospital with COVID-19 pneumonia, SARS-CoV-2 exposure, as reflected in the PCR cycle threshold (Ct), should be viewed as a predictor of adverse outcomes” he told Dr. Zacharioudakis. “High viral load has been shown to be a predictor of poor outcomes beyond age, other medical problems, and disease severity at presentation, suggesting that it can be used for risk stratification or triage of patients.”
Real-time RT-PCR (reverse transcriptase polymerase chain reaction) tests for SARS-CoV-2 are the most accurate class of COVID tests currently available and can scan and analyze the greatest amount of genetic material even in the presymptomatic stages. In this study, airway samples analyzed using RT-PCR technology were obtained from patients with nasopharyngeal swabs, the long swabs that are widely used in healthcare and public testing sites.
A cycle threshold is one of the results of the PCR technique and can be used as a substitute for the amount of virus detected on nasopharyngeal swabs. Since the Ct value is determined on most commercial RT-PCR test platforms, it can prove to be an easily available tool for the provider to stratify risk and triage patients hospitalized with COVID-19 pneumonia.
The researchers determined that the study endpoints would include whether a patient required mechanical ventilation or extracorporeal membrane oxygenation (ECMO), and whether the patient died in hospital or was discharged to a hospice. Statistical calculations were performed to determine how often the endpoints of patients who had high versus low viral loads were met after adjusting the patients’ co-occurring conditions (comorbidities) using the Charlson Comorbidity Index and how severe the pneumonia was at the time of presentation was as shown in the Pneumonia Severity Index.
“We know that the virus multiplies rapidly in the asymptomatic and early symptomatic phases of COVID-19,” said Dr. Zacharioudakis. “Our study is consistent with this conclusion, as evidenced by our finding of higher viral loads in patients who presented earlier with the disease.”
He added, “The study also found that patients with multiple comorbid conditions such as heart disease, diabetes, and cancer – or those who were immunocompromised from an organ transplant – were more likely to have higher levels of SARS-CoV-2 exposure in hospital and, as a result, one increased risk of poor results. “
A key feature of this study was that it focused on patients hospitalized for COVID-19 pneumonia, a group at high risk of serious illness or death. The fact that the link between the high viral load and poor patient outcomes persisted after considering patients’ underlying medical conditions, how long they were sick before they were hospitalized, and how sick they were at the time of presentation provides valuable evidence demonstrating the ability of SARS-CoV-2 viral load to predict COVID outcomes.
The authors note that in patients with severe clinical presentation, those with high SARS-CoV-2 viral loads were almost twice as likely to be intubated or die.
Dr. Zacharioudakis added, “Our study provides a justification for using the SARS-CoV-2 exposure of patients at the time of hospitalization to assess the risk of adverse outcomes. At a time when the availability of antiviral drugs is proving effective against COVID has shown that the ability to closely monitor is limited and limited, being able to prioritize those patients who will benefit most from early treatment or higher levels of care is of paramount importance, and further studies are needed to assess whether a decrease in viral load in patients hospitalized with COVID-19 who may or may not be treated with antiviral drugs such as remdesivir correlate with an improvement in clinical status. ”
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Ioannis M. Zacharioudakis et al. Association of SARS-CoV-2 Genomic Exposure with COVID-19 Patient Outcomes, Annals of the American Thoracic Society (2020). DOI: 10.1513 / AnnalsATS.202008-931RL Provided by the American Thoracic Society
Quote: The amount of COVID virus RNA detected at hospitalization predicts how patients will fare (2020, October 29). Retrieved October 29, 2020 from https://medicalxpress.com/news/2020-10-amount-covid-viral-rna-hospital. html
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