neonate testing

We used to report immune status as last serological reactivity at the highest serial dilution: if patient's serum gave a positive reaction at a dilution of 1:40 but not 1:80, then their "titer" was 1:40. Then clients began to get confused by different sources claiming different titers as the breakpoint for immunity or "immune status".

Then, technologies came about to measure antigen-antibody reactivity with color reactions (like EIA or ELISA) which could be expressed as various units per ml. These were then related to standards for immunity promulgated by the CDC (the federal Communicable Diseases Center in Atlanta) and expressed as ratios, multiples, or "titers" of that standard. Clients became confused, and we switched back to "positive" or "negative" for immune status. Immunity or immune status is assumed if the patient's reactivity is equal to the standard. If, after hepatitis B vaccination, your serum reactivity is a ratio 13.95 times the CDC standard, you are (by standard convention) not pressumed to be any more immune than one with a ratio of 1.0 times the CDC standard.

About 10% of the USA population is a group referred to as vaccination "non-responders". If your vaccination protocol requires serology testing for immune status after the vaccination shot series, a "nonresponder" is one who failed to mount enough antibody quantity to achieve "immune status: positive". If a person was not tested for immune status following vaccination and the status must be determined later and is found to be negative, the following will help decide whether (1) they responded but current antibody level is lower than the breakpoint between "positive" & "negative" vs. (2) or they are a "nonresponder". Give a vaccination shot now and retest "immune status" serology in 3-4 weeks. A respponder will become "immune status: positive" and a nonresponder will still remain "immune status: negative".

  (posted 6 November 2002; latest update 1 March 2007)