Testing for SARS-CoV-2 antibodies

As the covid-19 pandemic has unfolded, interest has grown in antibody testing as a way to measure how far the infection has spread and to identify individuals who may be immune.1 Testing also has a clinical role, given the varying symptoms of covid-19 and false negative results of reverse transcription polymerase chain reaction (RT-PCR) tests, particularly when swabs are taken more than five days after symptom onset and sensitivity of RT-PCR tests starts to decrease.23 In May, the UK government announced that antibody testing should be offered to anyone having their blood taken who wants to know whether they have been infected with SARS-CoV-2, even if there is “not a specific clinical indication,”4 yet currently there is no clear guidance for clinicians on how to interpret these results or how they fit into clinical pathways. In this article we offer an approach to antibody testing in individuals with and without symptoms suggestive of current or past SARS-CoV-2 infection.