THE ASSOCIATION between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid (N) antigen levels and hospitalised patient outcomes was evaluated in a recent study. Previous studies have shown that higher levels of plasma SARS-CoV-2 RNA are linked to critical illness, non-pulmonary organ failure, intensive care unit admission, and mortality. The aim of this study was to determine if the levels of plasma SARS-CoV-2 N antigen could be used to evaluate short-term outcomes in patients.
The study included 2,694 patients enrolled between August 2020 and November 2021. The participants were randomly assigned to be treated with either bamlanivimab, sotrovimab, amubarvimab-romlusevimab, tixagevimab-cilgavimab, or a matched placebo. A microbead-based immunoassay was used to quantify the plasma SARS-CoV-2 N antigen.
Additionally, a surrogate viral neutralisation test was used to assess the anti-spike neutralising antibodies. Calculation of the percentage of binding blocking the antibodies in the patient was determined by the assay, and an outcome of 30% or above in binding was regarded as positive. Researchers also analysed the anti-N pan-immunoglobulin positivity.
The findings showed that at the time of enrolment, 52% and 62% of the participants tested positive for the SARS-CoV-2 anti-spike antibody and positive for anti-N antibody, respectively. Furthermore, 28% of the patients were negative for both anti-N and anti-spike antibodies. The research team found that 57% of patients had elevated plasma antigen levels. It was observed that the patients who had symptoms for 1 week or over had higher plasma antigen levels. This, however, decreased following <2 days of remdesivir treatment and increased duration of hospitalisation. Older patients, especially those above the age of 65, had elevated plasma antigen levels. Additionally, patients with renal impairment had higher plasma antigen levels. The results of the study demonstrated that increased levels of SARS-CoV-2 N antigen were significantly linked to the severity of COVID-19 and patient outcomes.