Evaluation of viral loads in patients with SARS-CoV-2 Delta variant infection: Higher loads do not translate into different testing scenarios

The Delta SARS-CoV-2 variant is very infectious, and it is spreading quickly during this pandemic. In the study, we compared viral loads in surging cases infected with the SARS-CoV-2 Delta variant in the fourth wave of COVID-19 with the three prior waves. The data comprised viral loads from positive cases detected within the UPMC health care system in Allegheny County, Pennsylvania. A total of 2,059 upper airway samples were collected and tested for SARS-CoV-2 positive by RT-PCR during March 2020-September 2021. We did not observe significant difference in viral load difference between the third (December 2020 – January 2021) and fourth (June 2021 – September 2021) waves; however, they had the higher viral load than the first (March 2020 – June 2020) and second waves (June 2020 – August 2020). We did find an age-related effect with the elderly presenting with lower viral loads, which was also seen in the earlier waves. However, the level of viral load in the fourth wave was not sufficient higher to qualitatively change our expected detected rates using various testing modalities.