Throughout the COVID-19 pandemic, researchers have tried to identify early indications of disease severity in patients at higher risk for complications, such as people with obesity or people over the age of 65. Recent studies by Yale show promising results that saliva tests and blood tests may allow doctors to predict how severe patient symptoms will be on a case-by-case basis.
While similar in outcome, the studies each took largely different approaches to the topic: one study examined the accuracy of a saliva test while the other examined blood testing. This begs two questions: what is the difference between the two tests, and will either provide accurate predictions?
Predicting COVID-19 Severity Using Saliva
While simpler in use than the standard nasal-swab currently performed in COVID-19 testing, the saliva collection technique is only available today at select laboratories. Saliva COVID-19 testing is not currently available to most people, but researchers have become increasingly interested in the potential of the saliva testing method.
Research on the saliva test shows that patients with increased SARS-CoV-2 viral load could be more susceptible to disease complications. Unlike the nasal-swab testing method, the saliva test can provide information on the condition of a patient’s lungs. Mucus regularly travels via cilia (hair like structures) from the lungs to the throat where it combines with saliva; if the virus is found in saliva, it is possible that the virus has entered the lungs — where COVID-19 complications are typically most severe.
According to the preliminary results of the study, saliva viral load directly relates to disease severity, as well as other parameters tested by Yale. These include obesity, age, immune response and more.
Blood Testing Evaluates Biomarkers
Much like the saliva-based study, the blood test study aimed to find early predictors in patients who later developed severe COVID-19 complications. Researchers found that certain biomarkers associated with white blood cell activation were potential early complication indicators.
While blood samples were only taken from 100 patients, a clear pattern in results emerged. Those who later experienced critical illness in relation to COVID-19 showed increased levels of five proteins related to neutrophils, a type of inflamed white blood cell. Those who did not experience symptoms or complications did not show the increased protein levels or neutrophil biomarkers.
Results from this study note that neutrophils are increased in both cases of COVID-19 and obesity. These biomarkers appeared in COVID-19 patients before they began to experience symptoms and were not previously associated with COVID-19. While neutrophils are common in infections and other causes of inflammation (such as obesity), understanding the link between neutrophils and COVID-19 can help doctors better predict severity and treat patients accordingly.
The Bottom Line
Both studies have provided insights in the hunt for new information about early indication of COVID-19 complications. While each study requires expanded research before public use and implementation, both collaboratively provide a glimmer of hope for COVID-19 treatment and preparedness.