The perception of a company can often be overwhelmed by the success of a single one of its products. Investors counting the tens of millions of iPhones sold every quarter over the past decade whipsawed Apple's stock up and down based on numbers that, in hindsight, weren't that important. To a lesser degree, the same thing may now be happening to Pfizer (NYSE:PFE). News of potential COVID-19 vaccines seems to refresh every day, and with it, investors' expectations. But there are more reasons to buy Pfizer stock than just the headline-grabbing coronavirus vaccine, BNT162b2.

A woman working on a pharmaceutical manufacturing line in protective gear.

Image source: Getty Images

1. Vaccines (plural)

Of course discussions of Pfizer start with the company's COVID-19 vaccine -- developed with partner BioNTech (NASDAQ:BNTX) -- to prevent infection by the SARS-CoV-2 virus. The vaccine, which uses messenger RNA (mRNA) technology, has demonstrated 95% effectiveness in preventing COVID-19. Just this week, the vaccine was administered to the first patients in the U.K. and received distribution approval in Canada. After the U.S. Food and Drug Administration (FDA) confirmed the positive results on Dec. 8, approvals in the U.S. are almost certainly close behind. An FDA advisory board is set to meet today, Dec. 10, to discuss Pfizer's application for BNT162b2's Emergency Use Authorization (EUA).

What people may be surprised to learn is the company's best-selling drug is already a vaccine. 

Prevnar 13, a vaccine against pneumonia, meningitis, and ear and sinus infections brought in $5.85 billion worth of sales in 2019. That is compared to $5.8 billion and $5.6 billion in 2018 and 2017, respectively. Although the drug's revenue was down slightly in the company's latest quarter, increased awareness of vaccines drove 14% growth in international markets. Awareness is not something that will diminish after the pandemic abates, and I would expect the continuous increase vaccine uptake to persist.

2. Ibrance

The company's second-best-selling product in 2019 was the breast cancer treatment Ibrance. Sales of the drug reached almost $5 billion in 2019, representing 20% growth over 2018 and 59% growth from 2017. The company signed an agreement with Olema Pharmaceuticals (NASDAQ:OLMA) to supply the drug for its clinical trials in a combination therapy. Unfortunately, two other studies of the drug in combination did not clear hurdles for effectiveness.

These combination therapies to improve on established results are important in order to hold off generic competition. Case in point: Pfizer has sued two drugmakers in India to block their plans to release generic versions of Ibrance prior to its patent expiration in 2023. For now, the drug dominates the category. On the most recent earnings call, CEO Albert Bourla said more than 8 of 10 U.S. metastatic breast cancer patients who were prescribed a CDK4/6 inhibitor -- drugs that disrupt how breast cancer cells divide and multiply -- were prescribed Ibrance.

3. Emerging demand

By some estimates, 59% of the world's population lives in emerging markets. As prosperity increases in these countries -- the International Monetary Fund (IMF) expects emerging markets to grow 33% faster than their developed counterparts -- these global citizens expect the same standard of living that they see in other parts of the world. Pfizer's size and geographic diversity will allow it to be a leader in the developing world as the demand for life-improving pharmaceuticals increases with standards of living. This opportunity exists for both branded and generic drugs.

In fact, it's already happening. In the U.S., the company's overall sales fell 8.4% from 2017 to 2019. In the developed countries of Europe and the rest of the world, sales were flat over the same time period. However, in emerging markets, sales rose 11.7%. The most recent quarter saw international sales of Prevnar 13 and Ibrance up 14% and 26%, respectively. 

Pfizer's recent simultaneous spinoff and merger of Upjohn -- Pfizer's generics business -- with Mylan is part of its strategy to focus on these markets. The business combination, Viatris (NASDAQ:VTRS), which Pfizer retains a 57% stake in, is better able to focus on these growing areas with dedicated regulatory, marketing, and manufacturing for these geographies. 

Should investors care about the coronavirus vaccine's success?

In short? Yes. Pfizer and BioNTech could evenly share as much as $8.1 billion in revenue over the entirety of 2021, according to analysts at Mizuho Securities. That is no small sales opportunity. However, Pfizer has already proven its longevity with its line-up of already-approved drugs and increased access to nascent addressable markets. Even if you've been totally ignoring coronavirus vaccine news over the past nine months, you'd be right to think that Pfizer was a great buy-and-hold stock.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.