Associations Between Relative Viral Load at Diagnosis and Influenza A Symptoms and Recovery

Open Forum Infectious Diseases

Corresponding Author: Andreas Handel

Summary by Kailah Massey

Diagnostic polymerase chain reaction (PCR) tests are a method to determine the presence of pathogens. PCR tests provide a qualitative positive or negative result only. Such information is beneficial for making decisions about treatment. Currently, the Cobas Liat system provides a similar qualitative result based on the internal threshold of visual brightness. The Cobas Liat system provides the results as either positive (a presence of the pathogen), or negative (an absence of the pathogen). This quantity can provide physicians with additional information that can help decide the correct treatment for patients. 


A group of scientists including CEID member Andreas Handel conducted a prospective, nonrandomized, sequential-patient design study that assesses the correlations between relative viral load, the concentration of the pathogen, and influenza A symptoms. The study consisted of outpatient-based PCR results from the Cobas Liat test to determine whether viral load quantities provided valuable information about the disease progression and recovery of a patient. This team’s study is unique in that the population in the study was from a primary care setting, involved a point-of-care PCR test, and included outcomes for disease progression five days after the patient’s visit. The objective of their analysis is to determine whether the relative viral load at diagnosis, has probable relevance to physicians for treatment or can predict the speed of recovery. 


The study included students at a university health center who presented with a cough and one additional flu-like symptom from December 2016 to February 2017. Data was then collected before, during, and five days after the patient’s clinic visit. Samples were analyzed for correlations between the relative viral load, disease severity, and recovery, for all patients that tested positive for influenza A. Disease severity was measured using a total symptom score was created and consisted of two versions. The first version is based on the symptoms reported by the physician at the time of the diagnostic test. The second was the self-reported symptoms from the patient before the diagnostic test. 


The results of the study included a positive correlation between viral load and body temperature. There were no correlations between viral load and overall symptom severity, or outcomes related to recovery. The scientists argued that relative viral load can be the most advantageous variable if it were predictive of disease progression and outcomes. If it were it would provide physicians with additional predictive information. Future studies have the potential to analyze additional correlations between different types of populations and groups of people. The viral load may contain important information that is independent of specific groups of patients. Such findings can help to further treatment and disease outcomes for influenza A and similar pathogens. 


Brian McKay, Mark Ebell, Wesley Zane Billings, Ariella Perry Dale, Ye Shen, Andreas Handel, Associations Between Relative Viral Load at Diagnosis and Influenza A Symptoms and Recovery, Open Forum Infectious Diseases, Volume 7, Issue 11, November 2020, ofaa494,