*PPSV does not induce T-cell dependent immunity
*PCV induces T-cell dependent immunity
*why PPSV still has efficacy in older population while PCV couldn't show higher efficacy than PCV for older population?
*new product "Pneumosil" from India
**10-valent
**serotypes 1, 5, 6A, 6B, 7F, 9V, 14, 19A, 19F, 23F
*the reason why PCV13 for older population failed to show persistent efficacy against IPD in the U.S. may be contributed by spread of PCV13 for children which has caused serotype substitutions in community