Antibody Tests ID COVID-19 Two to Three Weeks After Symptoms
After onset of symptoms, sensitivity is low in first week, increases in second week, peaks in third week
MONDAY, June 29, 2020 (HealthDay News) -- Antibody testing may detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, with sensitivity peaking at three weeks since symptom onset, according to a review published online June 25 in the Cochrane Library.
Jonathan J. Deeks, Ph.D., from the University of Birmingham in the United Kingdom, and colleagues examined the diagnostic accuracy of antibody tests to determine whether a person has SARS-CoV-2 infection or has previously had SARS-CoV-2 infection. Data were included from 57 publications reporting on 54 study cohorts with 15,976 samples; 8,526 were from cases of SARS-CoV-2 infection.
Forty-four studies only included people hospitalized due to suspected or confirmed COVID-19 infection; no studies were conducted exclusively among asymptomatic participants. The researchers found that the pooled results from immunoglobulin (Ig)G, IgM, IgA, total antibodies, and IgG/IgM all demonstrated low sensitivity in the first week since symptom onset (all <30.1 percent), increasing in the second week, and peaking in the third week. The combination of IgG/IgM had sensitivity of 30.1, 72.2, and 91.4 percent for one to seven, eight to 14, and 15 to 21 days, respectively. Pooled sensitivities for IgG/IgM were 96.0 percent for 21 to 35 days.
"While these first COVID-19 antibody tests show potential, particularly when used two or three weeks after the onset of symptoms, the data are nearly all from hospitalized patients, so we don't really know how accurately they identify COVID-19 in people with mild or no symptoms, or tested more than five weeks after symptoms started," Deeks said in a statement.