Researchers from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH, Bethesda, MD, USA), and their collaborators analyzed levels of SARS-COV-2 antigen in blood samples taken from study participants and assessed the association of those levels with disease progression following the ACTIV-3 trial of COVID-19 therapeutics in people hospitalized with COVID-19.More severe sickness was associated with higher levels of viral antigen in the blood, which could imply ongoing SARS-CoV-2 replication. According to the researchers, SARS-CoV-2 antigen levels have promise as a biomarker, or measurable chemical, for predicting which patients hospitalized with COVID-19 are at a higher risk of poor outcomes.
Between August 2020 and November 2021, persons hospitalized with COVID-19 were enrolled in the ACTIV-3 experiment. Participants provided a baseline blood sample before being randomly assigned to either an investigational COVID-19 treatment or a placebo. Unless contraindicated, all individuals got the antiviral remdesivir. In this follow-up study, the researchers looked at SARS-CoV-2 antigen levels in 2,540 baseline blood samples from participants. The researchers looked examined the association between each participant's SARS-CoV-2 blood antigen levels and the time it took them to get out of the hospital, as well as their pulmonary symptoms on day five of the experiment, to see if they had stayed the same, worsened, or improved since enrolment.
With all of this data, the researchers ran statistical analyses to see if plasma antigen levels were related to the individuals' pulmonary function when they submitted the blood sample - and if they could forecast how the people would perform over time. Furthermore, the researchers investigated the association between a variety of participant and virus characteristics, as well as antigen levels.
High blood antigen levels were also linked to certain established risk factors for worse illness, such as male gender. Three other participant features were discovered to correlate with decreased antigen levels: the existence of SARS-CoV-2 antibodies, prior exposure to remdesivir, and a longer stay in the hospital prior to participation.Finally, people infected with the delta variation exhibited higher antigen levels than people infected with previously circulating strains. The researchers found that antigen levels in the blood are most likely a sign of ongoing viral replication and could be useful in predicting illness progression and outcomes once a patient is admitted to the hospital. According to the researchers, these findings suggest that a precision medicine strategy could be beneficial in future clinical trials of antiviral medication. Antigen levels, for example, could aid in determining which patients are most likely to benefit from virus-fighting medicines.
