Don't always believe the conventional wisdom. For example, many assume that stocks that have fallen are always more attractively valued than stocks that have risen. That's often the case. However, it's not always true.

Granted, it's not necessarily easy to find stocks that have strong momentum yet are still bargains. But they do exist. Here are three red-hot stocks that are still dirt cheap.

Smiling person lying on a sofa with hands in the air looking at a laptop.

Image source: Getty Images.

BioNTech

There's no hotter vaccine stock on the market right now than BioNTech (NASDAQ:BNTX). Its shares have skyrocketed more than 245% higher year to date. And that momentum isn't fading.

But is BioNTech really dirt cheap? Yep, at least based on two commonly used valuation metrics. Shares of the German biotech currently trade at close to 7.4 times expected earnings. BioNTech's price-to-earnings-to-growth (PEG) ratio based on five-year projected earnings growth stands at only 0.06. That's super-low.

The company's valuation hinges on increased sales expectations for the COVID-19 vaccine that it developed with Pfizer. BioNTech and Pfizer look for the vaccine to rake in sales of around $26 billion this year. The partners split profits from the vaccine equally.

BioNTech's shares are trading at a seeming bargain because investors aren't sure how much recurring revenue the company will be able to count on after 2022. If booster doses are needed going forward, BioNTech's future sales could be massive for a long time to come. 

Novavax

Novavax (NASDAQ:NVAX) ranks as another vaccine maker that's on a roll. Its stock has soared over 80% year to date after rising 2,700% in 2020. 

We can't use earnings-based valuation metrics with Novavax because it isn't profitable yet. However, looking at the company's forward price-to-sales (P/S) multiple is fair game. The consensus analysts' estimate is that Novavax will generate sales of $5.2 billion next year. With Novavax's market cap currently at close to $15.5 billion, the company's shares are trading at a little under three times expected sales. That's cheap for a biotech stock.

There's one big caveat for Novavax: It needs to win emergency use authorizations (EUA) for its COVID-19 vaccine, NVX-CoV2373. However, the company has already announced positive results from two late-stage studies for its vaccine. Novavax plans to file for EUA in the U.S., U.K., and European Union within the next couple of months.

Unlike BioNTech, Novavax has also already reported positive late-stage results for another vaccine candidate. Experimental flu vaccine NanoFlu was Novavax's crown jewel before the COVID-19 pandemic hit. The company hopes to pair up NVX-CoV2373 and NanoFlu and arguably stands as the leader in developing a combo COVID-19/flu vaccine.

Owens & Minor

COVID-19 also helped put Owens & Minor (NYSE:OMI) on our list. Shares of the healthcare solutions company are up more than 70% so far this year. In 2020, Owens & Minor stock delivered a 423% gain.

The impressive stock performance for Owens & Minor is due mainly to the company's fast-growing sales of personal protective equipment (PPE). Owens & Minor posted 10% year-over- year revenue growth in the first quarter and record-high earnings thanks in large part to higher demand for its PPE products due to the ongoing pandemic.

Despite the big returns, Owens & Minor stock remains inexpensive. Its shares currently trade at less than 13.7 times expected earnings. By comparison, the S&P 500 index forward earnings multiple is 21.6. 

Owens & Minor's management team does expect PPE demand will moderate later this year. However, the company also thinks that long-term demand will remain well above pre-pandemic levels. 

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.