What should you do with Pfizer (NYSE:PFE)? Despite announcing a string of positive news over the last few months, the big drugmaker's shares have gone down instead of up. 

It's possible that a light will click on for investors, leading to a sustained uptrend for Pfizer. However, it's also possible that the pharma stock will continue in its state of malaise. Here are three reasons to buy Pfizer -- and one reason to sell.

Man with hands on his hips looking at lighted images of sell with a down arrow and buy with an up arrow with stock charts in the background

Image source: Getty Images.

1. Its COVID-19 vaccine

I'd argue that the top reason to buy Pfizer shares right now is its COVID-19 vaccine, Comirnaty (BNT162b2). Sure, the stock has fallen even as Pfizer's vaccine has been administered to millions of people and the company has announced multiple major supply deals. However, investors often have the same view as Cuba Gooding, Jr.'s character in the movie Jerry Macguire, who famously proclaimed: "Show me the money."

Pfizer already reported $154 million in sales for Comirnaty in the fourth quarter of 2020. The company will soon begin showing investors a lot more money from Comirnaty. Pfizer projected that the vaccine will generate sales of around $15 billion this year. Gross profits will be split equally between Pfizer and its partner BioNTech

However, that projection was based primarily on the number of doses that Pfizer was contracted to supply as of early February. Since then, the company has secured additional supply deals, one with the U.S. for another 100 million doses and another with the European Union for another 200 million doses. More supply agreements could be on the way.

Pfizer CEO Albert Bourla said in the company's Q4 conference call that a "durable COVID-19 vaccine revenue stream" similar to the seasonal flu is likely. He mentioned the potential need for regular booster shots to maintain immunity as well as the possibility for booster shots to combat new coronavirus variants. If Bourla is right, Pfizer could be showing investors big money with Comirnaty for a long time to come.

2. Its overall growth prospects

Even without Comirnaty, Pfizer's overall growth prospects look better than they have in years. The main reason is that the company no longer has legacy drugs that have lost patent exclusivity holding it back. All of those products went with Upjohn when the former Pfizer unit merged with Mylan to form Viatris (NASDAQ:VTRS) in November 2020.

Pfizer now expects to deliver annual revenue growth of around 6% and adjusted earnings-per-share growth of 10% at least through 2025. But those projections exclude any impact from the company's COVID-19 vaccine. They also don't factor in the possibility (probability might be the better word to use) of acquisitions and licensing deals to bolster the pipeline.

The company's current lineup includes multiple big winners such as blood thinner Eliquis, breast cancer drug Ibrance, and rare disease drug Vyndaqel. Pfizer also seems to have gotten better at developing new drugs, with a 21% end-to-end pipeline success rate compared to an industry average of 8%.

3. Its dividend

We certainly can't leave out Pfizer's great dividend as a top reason to buy the stock. The dividend currently yields north of 4.6%. 

In December, Pfizer announced that it was increasing its dividend payout by 3% starting with the 2021 Q1 dividend. This dividend will be the 329th consecutive dividend paid by the company. In Pfizer's Q4 call, CFO Frank D'Amelio said, "For the foreseeable future, we expect our board to continue to support annual dividend increases at approximately this year's level."

Investors should be aware that Pfizer plans to adjust its dividend downward once Viatris declares its own dividend. However, Pfizer shareholders who held onto their Viatris shares will receive the same combined dividend payment between the two companies.

And the one reason to sell

There's also one compelling reason to sell Pfizer. Actually, it's a good reason to sell any stock. If you have a more important or better use of your money, sell.

If you need to raise cash to make ends meet, selling Pfizer stock should be on the table. If you're an aggressive investor seeking huge returns, there are plenty of growth stocks to buy that will be a better fit for you. You might want to consider selling Pfizer to scoop up one of those stocks.

However, my view is that Pfizer is a solid pick for conservative investors looking for a combination of growth and income. I think that the company will have plenty of good news in future quarters that will at long last get the stock moving in the right direction.

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.