What measurement is often used by scientists to track long-term protection, reflecting the concentration of circulating antibodies?

Answer

Antibody titer

Antibody titer is the term used to describe the concentration level of protective antibodies currently circulating in a person's blood, often used as an indicator of immediate protection potential.

What measurement is often used by scientists to track long-term protection, reflecting the concentration of circulating antibodies?
biologymedicinevaccineimmunitylong-term