But the old Merck vaccine, called a polysaccharide vaccine, has several problems that have limited its use.

FORBES: Pfizer's Vaccine Plan

This means that doctors wait to give the polysaccharide vaccine until the patient seems most at risk.

FORBES: Pfizer's Vaccine Plan

C-reactive protein was first discovered in the 1930s as a protein the body made in response to a sugar (the C polysaccharide) made by bacteria.

FORBES: A New Age Of Statins?

The pneumococcal polysaccharide vaccine is for everyone 65 and up.

FORBES: Shots for Grown-Ups

One showed that when patients who had already received the polysaccharide vaccine were given Prevnar 13, their immune responses were better than those who got another dose of the polysaccharide vaccine.

FORBES: Pfizer's Vaccine Plan