Lecture Notes on Immunity and Vaccination

Flashcards about herd immunity, antibody titer, and vaccine principles.

Herd Immunity

A form of indirect protection from infectious disease that occurs when a large percentage of a population has become immune to an infection, thereby providing a measure of protection for individuals who are not immune.

Limitations of Herd Immunity

Herd immunity's effectiveness is reduced when a pathogen mutates or due to variations in exposure levels, genetics, and background factors among individuals.

Antibody Titer in Serum

The concentration of antibodies in the blood serum, often used to assess the level of immunity against a specific antigen.

Primary Response (Vaccine Context)

The immune system's initial response to an antigen, characterized by the production of IgM antibodies followed by IgG antibodies by plasma cells.

Secondary Response (Vaccine Context)

The immune system's response upon subsequent encounters with the same antigen, marked by a quicker, more drastic increase in antibody titer, predominantly IgG, due to memory B cells.

Memory B Cells

A subset of activated B-cells that do not become plasma cells but remain long-lived, enabling a rapid clonal expansion and stronger protective response upon future encounters with the same antigen; this underpins vaccine effectiveness.