Prevnar 20 is what’s called a conjugate vaccine. The antigens for the vaccine are polysaccharides, chains of sugar molecules from the bacteria’s outer coat. The polysaccharides are conjugated, or bonded, to a carrier protein. By carrying more of these polysaccharides, a vaccine can protect against more strains.
According to Pfizer, the seven additional strains covered in Prevnar 20 account for about 40% of all pneumococcal disease cases and deaths in the U.S. All 20 of the strains are estimated to be responsible for more than half of all U.S. cases of invasive pneumococcal disease, which include bacteremia and meningitis, as well as community-acquired pneumonia.
With Prevnar 20’s approval, Pfizer can claim it offers a vaccine that protects against more of the disease-causing pneumococcal strains than any other vaccine currently available. However, competition is on the way. Though Merck’s V114 protects against five fewer pneumococcal strains than Prevnar 20, the pharmaceutical giant is further along in clinical testing of its candidate in children. Last month, Merck reported positive
preliminary results of a Phase 3 pediatric test of its vaccine. An
FDA decision on V114 in adults is expected in mid-July.
