A positive test may not necessarily indicate active infection, since antibodies may persist for years. The titer is not directly correlated with the severity of the infection, due to the variance in patient response and to the variance in response to the type of infection. A negative response is equally important, as long as ample time has been allowed for antibody production.
Gold serum separator (SST) tube
Spin and separate
Enzyme immunoassay (EIA)