Pfizer-BioNTechPfizer’s (NSE:PFE) pneumococcal 13-valent conjugate vaccine Prevnar 13 is one of pharma’s bestsellers, earning nearly $6 billion last year.

Now, the company has scored FDA approval for its Prevnar 20 vaccine for adults 18 and older.

The vaccine is the first to offer protection against 20 serotypes of pneumococcal disease that cause the majority of pneumonia and invasive pneumococcal disease. In addition to the capsular polysaccharide conjugates already included in Prevnar 13, the new vaccine adds conjugates for seven different serotypes linked with invasive pneumococcal disease, antibiotic resistance and meningitis.

“With a single injection, Prevnar 20 provides adults with strong and meaningful protection against serotypes responsible for the majority of circulating pneumococcal disease around the world,” said Kathrin U. Jansen, senior vice president and head of vaccine research and development at Pfizer, in a statement.

Pfizer oversaw Phase 1 and 2 trials for the Prevnar 20 in addition to three Phase 3 studies for Prevnar 20.

Merck (NYSE:MRK) is currently working on an investigational 15-valent pneumococcal conjugate vaccine. The company now lags far behind Pfizer in terms of its pneumococcal vaccine sales.

Merck, however, recently announced that its V114 investigational 15-valent pneumococcal conjugate vaccine met its primary immunogenicity and safety endpoints in two studies.

Merck is also pursuing marketing authorization for the V114 vaccine.