What would happen if a company developed a massive new product and no one cared? For Pfizer’s (NYSE:PFE) investors, that has been the question for the past year. Despite coming up with a blockbuster vaccine for the novel coronavirus, PFE stock did basically nothing for an extended period.

That finally changed this summer, when Pfizer belatedly rallied to new all-time highs. Now though, the gains are fading almost as quickly as they happened. In its Q2 earnings release, Pfizer reported 93% year-over-year revenue growth. Yet shares are up less than 20% over the past 12 months. Why have investors not given Pfizer credit for its performance, and will that change in the future?

Vaccine Hits A Setback

Pfizer has enjoyed incredible revenue growth over the past year due to its Covid-19 vaccine. The majority of vaccinated American adults have taken the Pfizer vaccine, and it’s had strong sales overseas as well.

Despite that, however, PFE stock didn’t move too much. At least, not until July of this year. At that time, PFE stock finally took off. The reason why is that investors started to price in the expectation that people would need to take vaccine booster shots to maintain efficacy.

The idea of a third, and potentially even fourth or more dose of vaccines would have created a far more enduring revenue boost for Pfizer. Up until recently, investors had shied away from Pfizer despite its massive top-line growth because they anticipated that the Covid business would quickly recede. With booster shots, however, the vaccine would have taken on another level of importance to the company.

This scenario is now under increasing doubt, however. A Food and Drug Administration (FDA) advisory panel recently recommended against advising booster shots of the Pfizer vaccine. A large majority of the panelists voted that the data on hand was insufficient to warrant booster shots. That comes amid reports that Moderna’s (NASDAQ:MRNA) vaccine remains effective in a higher percentage of people than Pfizer’s after 120 days.

This is hardly the final word on booster shots or the efficacy of Moderna versus Pfizer. Pfizer’s investors shouldn’t discount the possibility that the FDA later comes around on additional rounds of the vaccine. For now, however, the prospects are looking more uncertain.

Baseline Valuation Is Not That Demanding

Let’s go back in time to 2019 and pretend that we’ve never heard of the pandemic. What does an investment in Pfizer look like in this hypothetical scenario? For full-year 2018, Pfizer generated $1.87 of EPS. In 2019, this leapt to $2.87.

Based on today’s stock price just below $44, PFE stock is selling at 23x 2018 earnings or 15x 2019 earnings. With no benefit from the current Covid-19 vaccine whatsoever, Pfizer stock would still be going for a reasonable multiple.

Yes, you can argue that pharmaceutical companies should trade for lower P/E multiples than many other industries given the high cost of drug development and quick patent expiries. Still, with earnings as strong as they were in 2018-19, it’s not hard to get behind the stock at $44 even if you give the company zero credit for the Covid-19 vaccine. Forget about booster shots for a minute, traders are pricing Pfizer like there will be little more revenue from the vaccine whatsoever.

PFE Stock Verdict

Right now, Pfizer stock is inextricably linked to its vaccine’s outlook. When there is positive news on that front, PFE stock surges. When there is a setback, PFE stock sells off hard. That’s a totally understandable market reaction. Many traders are trained to react quickly to the latest headline.

For longer-term investors, however, Pfizer is an opportunity regardless of the trajectory of the vaccine. Even if boosters ultimately aren’t a big thing, Pfizer can still make investors money from this entry point.

The company is a tremendous diversified pharmaceutical giant. It was in good shape long before the pandemic, and it has dozens of promising drugs in its pipeline to power it for the next decade and beyond. The company is reaping a windfall right now, but it’s not like that’s its only iron in the fire.

If the Covid-19 business continues longer than forecast, that’s all upside to the stock price. However, from this starting point, there’s sufficient margin of safety to support a purchase in most possible outcomes.

On the date of publication, Ian Bezek did not have (either directly or indirectly) any positions in the securities mentioned in this article. The opinions expressed in this article are those of the writer, subject to the InvestorPlace.com Publishing Guidelines.

Ian Bezek has written more than 1,000 articles for InvestorPlace.com and Seeking Alpha. He also worked as a Junior Analyst for Kerrisdale Capital, a $300 million New York City-based hedge fund. You can reach him on Twitter at @irbezek.