On Pfizer’s first-quarter earnings call, CEO Ian Read drew up a long list of R&D programs the company’s expecting to drive future growth. But when Bernstein analyst Tim Anderson asked him to narrow it down, Read mentioned vaccines first.

"It's difficult to pick out one specific product. But I would say when you look at the totality, I would focus on our vaccine franchise, especially C. difficile," said Read. He maintained that Pfizer pipeline is "undervalued," but the question is, could the collective vaccine pipeline make Pfizer watchers up their expectations? 

After Sanofi abandoned its Clostridium difficile vaccine last December in light of ominous phase 3 interim data, Pfizer’s PF-06425090 took over as the leading C. diff hopeful. The recombinant vaccine is undergoing a 16,000-patient phase 3 scheduled to read out in September 2020.

Analysts have pegged the C. diff vaccine market at about $1 billion, but Pfizer might have to split it with French firm Valneva, which has also passed phase 2 with its own candidate. And as GlobalData analysts previously said, the Valneva vaccine’s contrasting method of action "could give it an advantage when it comes to successfully meeting phase 3 trial endpoints."

Pfizer needs that C. diff boost to the top line, as its pneumococcal blockbuster Prevnar 13—the world’s best-selling vaccine—continues to decline. For the first quarter, global Prevnar 13 sales slightly decreased by 3% to $1.38 billion. While the precipitous 12% drop in the U.S. is particularly alarming, COO Albert Bourla turned to the 45% jump in emerging markets for a better picture.

"The most important is, we just launched in China, where we expect that we will have very good uptake," said Bourla, who recently took the COO title. But growth from China might not last for long. Local firm Walvax recently submitted to Chinese authorities its version of a pneumococcal 13-strain recombinant shot, which was put under expedited review in March.

Planning to fill the gap left by Prevnar, the New York pharma has a next-generation candidate that could cover 20 serotypes of pneumococcal disease. It expects proof-of-concept data later this year and plans to begin a pivotal trial in 2019. But competition awaits there, too.

Merck & Co.’s 15-valent shot V114 has just embarked on two phase 3 trials. For one of them, investigators will test it against Pfizer's 13-strain Prevnar shot, and Merck executives say they're confident their version can triumph.

"The serology data … are really very, very strong for the V114 vaccine. And it provides the opportunity to both strengthen the response to serotypes covered by other pneumococcal conjugate vaccines, but also to add additional stereotypes which will be important in terms of preventing invasive pneumococcal disease," said Merck R&D head Roger Perlmutter on the company’s Q1 call.

A partnership between Astellas and Affinivax is also working on a new challenger to Prevnar, but the competition between Pfizer and Merck seems more imminent. Bourla said he anticipates "launching in a competitive timeframe to Merck, a much broader spectrum of coverage quality."  

Other than those products, Pfizer has a phase 2 Staphylococcus aureus vaccine program, and the company is in discussions with the FDA about expanding that study into a phase 3 pivotal trial, Read said during the call.