4. Pfizer

Pfizer is competing with Merck to bring a more powerful Prevnar 13 follow-up vaccine to the market. (Pfizer)

2017 sales: $6.00 billion
2016 sales: $6.07 billion
Vaccine business led by: Susan Silbermann

Pfizer’s vaccines business has for years centered on Prevnar 13, the world’s bestselling vaccine, and 2017 was no exception. The pneumococcal shot accounted for 93% of the pharma giant’s $6.0 billion vaccines revenue last year.

But the company wants to change that—and for good reason.

Because Prevnar 13 uptake was so strong, especially in the U.S., the pool of potential recipients shrank markedly, pushing the Pfizer portion of Prevnar 13 sales down to $5.6 billion in 2017 from a high of $6.2 billion in 2015. In its June World Preview report, life sciences intelligence firm Evaluate predicted sales would remain stable through 2024, but relying too much on a single product is simply too risky in the long run. And not only because of a shrinking patient pool, but because Prevnar 13 faces patent challenges in several countries, including the U.S.

Competition is threatening, as well. Merck & Co. recently started two phase 3 studies of its 15-valent pneumococcal conjugate vaccine V114. One of those trials is pitting Merck’s candidate directly against the Pfizer shot. Evaluate analysts figure the Merck shot can nab $774 million in worldwide sales by 2024, not nearly as much as Prevnar 13, but still a big chunk of the market. And last February, Astellas partnered with Affinivax to use the latter’s Multiple Antigen Presenting System (MAPS) to develop a vaccine that they hope could cover more strains and elicit stronger immune responses than Prevnar 13.

RELATED: Merck pits its pneumococcal shot against Pfizer's mammoth Prevnar in head-to-head phase 3

Pfizer has a countermeasure, and it’s steadily moving ahead in the clinic—a vaccine that covers 20 serotypes. The candidate induced functional immune responses in phase 1, and with a phase 2 fully enrolled, Pfizer’s looking at phase 3 in 2019. Pfizer COO Albert Bourla said on the first-quarter 2018 call that the company anticipates “launching in a competitive time frame to Merck.”

And to hear Pfizer’s chief executive tell it, that follow-up pneumococcal candidate isn’t the only weapon in the company’s vaccines R&D arsenal. When asked by Bernstein analyst Tim Anderson on the first-quarter call to narrow down a long list of potential new revenue drivers in the pipeline, CEO Ian Read pointed to 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,” he said.

That candidate recently took over as the leading C. diff hopeful, after Sanofi’s shot failed a phase 3. Pfizer’s product, recombinant vaccine called PF-06425090, is undergoing testing in a 16,000-patient phase 3 trial scheduled to read out in September 2020. With that study underway, Pfizer and French firm Valneva are front runners toward the $1 billion C. diff vaccine market.

RELATED: Pfizer, Valneva stand to gain from Sanofi's C. diff vaccine flop: report

Other hopefuls in Pfizer’s pipeline include a phase 2 Staphylococcus aureus vaccine, an RSV vaccine only recently pushed into human testing, a maternal Group B streptococcus (GBS) shot, a prostate cancer vaccine and a Men ABCWY combo vaccine.

As those candidates make their way, Pfizer is hoping to reap more sales from its men B shot Trumenba. The vaccine gained EU approval last May for ages 10 or above, and it recently picked up an FDA “breakthrough” designation to reach children as young as 1 year. The challenge is GlaxoSmithKline’s market leader Bexsero, whose EU nod covers recipients from the age of 2 months. In 2017, Bexsero sales climbed to £556 million (about $776 million). As for Trumenba, it was lumped into Pfizer’s “all other vaccines” category, whose total sales in 2017 amounted to $266 million.

4. Pfizer