Pfizer (PFE -0.43%) is one of the top healthcare companies in the world. It is known for its COVID-19 vaccine and pill, plus an array of pharmaceutical products that help treat cancer, rare diseases, arthritis, and many other conditions and diseases.

This year, however, has been a tough one for the stock, with its shares slumping 19% since January -- only just slightly better than the S&P 500's 20% decline. Could this stock be a bargain buy right now? Or best to avoid, given the uncertainty it faces around its COVID-19 products?

Revenue remains a big question mark

A key reason investors have been bearish on the stock this year is concern for how strong the company's top line will be in 2023 and beyond. People aren't rushing out to get boosters. Data from the Centers for Disease Control and Prevention show that just half of the adults who have been fully vaccinated for COVID-19 have obtained their first booster shot. Demand looks to be declining, and unless there's a resurgence of COVID-19 cases, that's a trend that's likely going to continue into 2023.

For Pfizer, a company that is going to generate around $54 billion in revenue from both of its COVID-19 products this year (out of $102 billion in total revenue), that's troubling news as it suggests there is going to be a significant drop in sales next year.

The challenge for the company is how to make up for that shortfall. Pfizer has been acquiring companies within the past year to strengthen its pipeline, but many of those are long-term plays that won't come even close to making up for a decline in COVID-19 revenue.

Pfizer to raise prices for COVID-19 shot

In 2023, the government will no longer be buying COVID-19 vaccines as its supply runs out and a lack of funding prevents it from doing so. Instead, commercial market will determine the demand for vaccines moving forward. This gives Pfizer the opportunity to change the price for its shots, which it plans to do. Instead of the $30 per dose that the U.S. government is currently paying, Pfizer will charge between $110 and $130.

The increase in price will help to offset a drop in demand, but at the same time, it could hurt its competitiveness. Rival Moderna has estimated a price per dose between $64 and $100. And Novavax, which only obtained Emergency Use Authorization for its vaccine and booster this year, could also potentially undercut Pfizer on price.

Pfizer's substantial price increase could result in up to $3 billion of additional annual revenue for the business, according to one analyst estimate. But at the same time, it could destroy demand for the vaccine if companies aren't willing to pay that much for it -- a very realistic scenario at a time when inflation is a huge concern.

As a result, there remains plenty of uncertainty around the company's business heading into next year.

The stock is trading at a mammoth discount

One way investors can protect themselves when dealing with uncertainty is by paying a low multiple of earnings for a company. That way, if there's a significant decline in sales and profits, there's less risk of a sell-off. Today, Pfizer trades at less than 9 times its trailing earnings. To put that into perspective, that's almost near a 10-year low for the stock.

Although rising interest rates and inflation are reducing what premiums investors are willing to pay for stocks in the current market, Pfizer is still heavily discounted. By comparison, the average healthcare stock trades at an earnings multiple of 21.

Should you buy Pfizer stock today?

Pfizer's future over the next 12 months looks uncertain, but when you're investing over a time frame of five years or a decade, there becomes much less pressure for investors to worry about how the company will make up for lost COVID-19 revenue.

It could be a challenge, but Pfizer has a pipeline that featured a whopping 104 projects as of July, including 30 that were in late-stage trials. Somewhere along the way, it will develop products that will most likely help generate additional revenue. And if it still falls short, it can seek out more acquisitions -- the company has more than $33 billion in cash and short-term investments  as of July 3.

With a dividend that yields close to 3.6% right now, Pfizer looks like a steal of a deal. If you're a long-term investor, the short-term worries about the business shouldn't detract from what's still a top business in the healthcare industry.