Clinical Evaluation of Rapid Antibody Test for Covid-19

Rapid, accurate diagnosis of Covid-19 would greatly help to improve clinical management of patients presenting with symptoms of possible Covid-19. Currently results of the standard test for the virus take 2-3 days to be reported.

Watford General Hospital has imported rapid antibody tests manufactured by Zuhai Livzon Diagnostics Inc in China and our team would like to evaluate their accuracy and clinical usefulness. The test involves taking a drop of blood from the patient (either from a venous blood sample taken for other blood tests, or from a fingerprick). This is applied to a test strip (similar to a pregnancy test) and two drops of diluent are added. If the patient has antibodies to Covid-19, two lines appear on the test strip (like a positive pregnancy test) whereas if the patient has no antibodies, only one line appears (like a negative pregnancy test). There are two different types of antibody: IgM is produced early in the course of the illness (day 7-14) and then IgG is produced later and continues to be present, probably for months or years. There are two test strips, one for each of these types of antibody.

In this study we aim to evaluate the accuracy of this new test, in three groups of patients. Firstly those with proven Covid-19 and at least 7 days after the onset of their illness. We aim to recruit 200 patients in total: at least 138 patients with 10 or more days of symptoms, plus a subgroup of up to 62 patients with 7-9 days of symptoms (to explore the usefulness of the test earlier in the course of illness). The second group of 250 patients will be those hospital staff who report symptoms possibly caused by Covid-19 and are receiving a standard antibody test.

The third group of patients will be those followed up in a "virtual hospital" for clinically suspected Covid-19 who had never been tested with a standard PCR test.

As we are not sure of the accuracy of the new test, its results will not be used to make decisions about treatment for the patient.

This study will enable us to discover rapidly whether the new test is accurate, and if so we will conduct further studies to assess how it can help to improve management of patients with suspected Covid-19.