This technology includes a sensitive and specific method to rapidly detect antibodies in biofluids. This assay has been used for the detection of antibodies in blood, urine, and saliva. Until now, no one has used LIPS to detect clinically relevant antibodies to SARS-CoV-2 Nucleocapsid (N) or Spike (S) in saliva. Briefly, LIPS employs recombinantly synthesized target proteins or peptides (e.g., S and N proteins) tagged with light-emitting proteins as targets to be captured by host produced immunoglobulins. These immunoglobulins can be captured by protein A/G beads and immobilized. After immobilization, captured proteins tagged with luciferase can enzymatically react with substrate (luciferin) to emit light if captured, and then detected by a luminometer. The novelty of this method is that it can take less than 5 minutes, be scaled for use in a hand-held reader, and can be diversified to include a multitude of other detectable tagged proteins.