TABLE V.

Summary of PPV23-deficient response phenotypes

Phenotype*	PPV23 response, age >6 y	PPV23 response, age <6 y	Notes
Severe	<2 protective titers (>1.3 mg/mL)	<2 protective titers (>1.3 mg/mL)	Protective titers present are low
Moderate	<70% of the serotypes are   protective (>1.3 mg/mL)	<50% of the serotypes are protective   (>1.3 mg/mL)	Protective titers present to >3 serotypes
Mild	Failure to generate protective   titers to multiple serotypes   or failure of a 2-fold increase   in 70% of the serotypes	Failure to generate protective titers to   multiple serotypes or   failure of a 2-fold increase in 50%   of the serotypes	2-Fold increases assume a prevaccination titer of less than   cutoff values of 4.4–10.3 µg/mL, depending on serotype
Memory	Loss of response within 6 mo	Loss of response within 6 mo	Adequate initial response to >50% of the serotypes   in children aged <6 y and >70% in those aged >6 y

^*All phenotypes assume a history of infection. Reproduced from Orange et al¹⁷⁹ with permission.