COVID-19 IgG/IgM antibody testing in Los Angeles County, California

Abstract

Evidence suggests that asymptomatic and mild SARS-CoV-2 infections comprise > 95% of all cases. Developing a test that indicates past infection and possible immunity against the virus is important. We administered 244 antibody tests to three groups of high-risk population. The test consisted of an IgG component and an IgM component. The overall IgM/IgG positivity for patients with none, mild, moderate, and severe symptoms were 21.1%, 21.8%, 14.2%, and 26.9%, respectively. Those with moderate or severe symptoms were no more or less likely to have positive antibody tests than those with no or mild symptoms.

COVID-19 testing in Delaware’s underserved communities: demographic and social determinants of testing inequality

“…Typically, these antibodies (i.e., IgG and IgM) are produced as part of the body’s immune response. These antibodies have been found to be present in those who were symptomatic or asymptomatic as early as 14 days after symptom onset [ 2 , 3 ]. The sensitivity and specificity of the test were found to be greater than 90% for detecting the presence of viral infection from samples of human blood [ 3 ], with IgG antibodies detectable more than four months post-infection [ 13 ].…”

“…However, the antibody test might also show a positive result among those who had recently been vaccinated for COVID-19. Therefore, for the purposes of the present analysis, we coded a serology test as positive if the participant (1) received a positive result on the serology test and (2) had not yet received a single dose of the vaccine.…”

“…An antibody test can detect the presence of IgG and IgM antibodies typically found in individuals with previous coronavirus infection (SARS-Co-V-2). The IgG and IgM antibodies are produced as part of the body’s immune response in both symptomatic and asymptomatic cases and can be detected as early as 14 to 48 days post-infection [ 2 , 3 ]. The serology test has public health value for monitoring and responding to the ever-changing pandemic, especially when tracking past infections, which are not always detectable by tests for the virus [ 4 ]; however, both the CDC and the FDA have indicated that antibody testing cannot be used to replace tests for the virus in detecting current COVID-19 infection.…”

“…The ages of respondents in the sample ranged from 18 to 94 2. Nurses, student interns, staff, and participants wore masks at all times, sanitized their hands and IPADs frequently, and remained 6-feet apart.…”