October 18, 2020

WSU team’s study shows COVID-19 viral load declined as pandemic progressed

A team of physicians and researchers led by Pranatharthi Chandrasekar, M.D., Wayne State University School of Medicine professor of Internal Medicine and chief of the Division of Infectious Diseases, found that the viral load in nasopharyngeal samples in patients with COVID-19 decreased as the pandemic continued, and that the decline was associated with a decrease in the rate of death from the disease.

Presented virtually at the European Society of Clinical Microbiology and Infectious Diseases Conference on Coronavirus Disease Sept. 23-25, the study showed that the decline in the viral load was associated with a decrease in the death rate of those infected with COVID-19 during the period between April 4 and June 5.

“A decline in the initial viral load on presentation may represent a decrease in the exposure to the virus after widespread implementation of social distancing measures and use of facemasks in public,”

Said El Zein, M.D.

said Said El Zein, M.D., junior chief medical resident in the Wayne State University Deparatment of Internal Medicine, who presented the study. “A link between viral load and mortality has been suggested in multiple studies, therefore, this decline in viral load may reflect a decrease in mortality from the virus. In our study, we noticed that a declining viral load was associated in a linear fashion with decreasing death rates, however, an association between viral load and mortality cannot be assumed because we did not account for confounding variables.”

While the exact reason for the decrease in the initial viral load are unclear, Dr. El Zein said, the decreasing trend in the initial viral load could represent a reduction in the severity of the pandemic, with trends over time serving as a marker to assess the progress of the pandemic. He again stressed that rapid implementation of lockdown, social distancing and the widespread use of masks may have contributed to a decrease in exposures.

The team based its retrospective study on nasal swab samples from 708 patients hospitalized with COVID-19 at Detroit Receiving Hospital, Harper Hospital and Sinai Grace Hospital. They established a three-tier viral load measurement. During the first week of the study, the samples indicated the initial viral load was predominantly (48.7%) in the intermediate group. After that first week, they saw the viral loads drop, and by week five of the study, 70% of the positive samples fell into the low viral load category.

That decrease coincided with a drop in the percentage of patient deaths. Almost half of the patients in the high viral load group died, compared to 32% and 14% in the intermediate and low viral load categories, respectively.

The team plans to continue the study to determine trends in patients hospitalized for COVID-19 after the initial six weeks of its investigation.

Others involved in the study include Nivine El-Hor, M.D.; Omar Chehab, M.D.; Tushar Mishra, M.D.; Samer Alkassis, M.D.; Vichar Trivedi, B.S.; and Hossein Salimnia, Ph.D.