![]() The likelihood of false positive results can be reduced by using antibody tests that are highly specific (nearly 100% specificity) for SARS-CoV-2.Įven extremely accurate antibody tests could still be problematic, since we don’t yet know whether the presence of antibodies is indicative of true immunity and if it is, how long immunity lasts. ![]() ![]() Such results could cause susceptible people to believe they’re immune to COVID-19 and they might stop physical distancing measures and put themselves into risky situations where they could become infected. An antibody test might miss a case of infection, especially if the test is performed within two weeks of developing symptoms, before any antibodies have formed, or after several months, after antibody levels have waned.Īdditionally, an antibody test might mistakenly identify antibodies to a different coronavirus, such as one of the strains that causes the common cold, leading to a “false-positive” result. Like all diagnostic tests, COVID-19 antibody tests have important limitations. Talk to your healthcare provider if you are wondering if an antibody test is right for you. Whether immunity to COVID-19 might last a few weeks, a few years, or for life is also an open question.īecause antibodies to SARS-CoV-2 begin to wane within weeks of infection, for most people antibody tests won’t yield helpful information. Most infectious disease experts agree COVID-19 probably does induce some degree of immunity in those who recover from it, but this has yet to be proven. What remains to be seen is whether antibody tests can determine immunity to COVID-19, either due to having recovered from the illness or due to vaccination, once a vaccine becomes available. Individuals who suspect they previously had COVID-19 but test negative for antibodies might be more likely to exercise caution in their daily activities, which can help slow the spread of the virus. This can help resolve diagnostic uncertainty about a prior illness, and provides important information to epidemiologists trying to understand the extent of viral spread in a community.Ĭonversely, antibody tests can identify people who don’t have antibodies and who are therefore susceptible to COVID-19. We don’t know for sure whether antibodies to SARS-CoV-2 are long-lasting, or whether the severity of illness affects the durability or effectiveness of the antibodies.Īntibody tests have the potential to identify people who were previously infected with COVID-19 and have recovered. At this point, it appears that levels of some COVID-19 antibodies decline dramatically after several weeks, but likely persist at low levels and could be quickly reproduced by the immune system if it encounters the virus again. ![]() We do not yet know what level of IgG antibodies, if any, are indicative of immunity to COVID-19, but research is underway and we expect to have an answer to this question in the future.Īntibodies to some diseases last a lifetime, while antibodies to other diseases may disappear over time. IgG antibodies may confer immunity, or resistance to reinfection with the same virus, as is the case for diseases like measles, hepatitis A, and polio.īecause antibodies to a virus can only be produced if someone has been exposed to the virus or to a vaccine (which is still in development for COVID-19), the presence of antibodies to SARS-CoV-2 is a good indicator that the person has been infected with that virus at some point in the past. ![]() Over the course of an infection, the immune system produces different types of antibodies including IgM, which develops within a few days of the onset of an infection, and IgG, which develops several days or weeks later. Antibodies, also known as immunoglobulins (abbreviated Ig), are infection-fighting proteins created by the immune system in response to the unique characteristics of an infectious agent. ![]()
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