Results
We demonstrate that NCP antigen levels in serum remained elevated in 45.6% of patients requiring treatment on intensive care units (ICU) after >8 days post positive SARS-CoV-2 PCR, compared to complete clearance in all non-ICU patients. This was in contrast to mucosal clearance of virus as measured by PCR. Antigen clearance was associated with higher IgG against S1 but not NCP.