Immune Response and Antibody Production

Immune Response to Viral Infections

• When a person is infected with a virus such as SARS-CoV-2, the body initiates an immune response.
• The virus circulates within the body, prompting the production of antibodies.
• These antibodies target and eliminate the virus from the system; this is a fundamental aspect of immunology.

Serology and Antibody Detection

• Serology can be employed to ascertain whether an individual who contracted COVID-19, even asymptomatically, has been infected; this can be done within 3-10 days of infection.
• The body exhibits an increase in Immunoglobulin M (IgM) initially.
• Subsequently, around 7-14 days post-infection, Immunoglobulin G (IgG) levels rise; this timeframe can vary depending on the specific virus.
• IgG represents the later and more enduring immune response.

IgM Dynamics

• In a healthy individual, IgM levels increase before IgG levels.
• The presence of IgM indicates a recent infection.
• During the middle to later stages of an active COVID-19 infection, IgM levels begin to rise.
• IgM is cleared from the body more rapidly than IgG.
• IgM detection aids in determining recent infection status, and in some instances, whether the person is still infected.

IgG Dynamics

• IgG levels start to surge, particularly as IgM levels decline.
• IgG serves as an indicator of long-lasting immunity or a sustained immune response.
• Even in asymptomatic cases, individuals may exhibit IgG antibodies against COVID-19 in population samplings, signifying prior infection and a successful immune response.

Immunity and Immunoglobulin G

• When assessing immunity to a virus or disease, the focus is primarily on Immunoglobulin G due to its longevity.
• IgG presence confirms prior infection and subsequent recovery.