Disclosed herein are methods of performing multiplexed serological immunoassays to detect multiple antigens in parallel to determine if a patient has an infection or an immune disorder. Use of multiple antigens in parallel increases specificity and/or sensitivity towards assaying the infection or immune disorder. The infection may be a viral infection such as a SARS-CoV-2 viral infection, a variant of a SARS-CoV-2 viral infection, or a non-SARS-CoV-2 coronavirus infection. Also disclosed herein are methods of performing the multiplexed serological immunoassays on an optical ring resonator substrate. Also disclosed herein are methods of detecting antibodies specific for an antigen that belong to more than one immunoglobulin type.