Anything can happen in the short term, so it's folly to say that a stock is a sure thing for a quick double. Nonetheless, these Fool.com contributors are bullish on these three healthcare stocks, and there are reasons for short-term optimism.

Read more to find out why we think Novavax (NVAX -2.51%)Sorrento Therapeutics (SRNE.Q 1.82%), and InMode (INMD -0.96%) will close out 2021 with a bang.

Healthcare worker holds up a vial of blood to be checked for COVID-19.

Image source: Getty Images.

1. Multiple catalysts will make Novavax shares jump in 2021

Taylor Carmichael (Novavax): Novavax stock has already doubled this year, running from $112 back in January to $233 this week. But there's plenty of gas left in the tank, and I expect another double by the end of the year.

Right now, Moderna enjoys a $169 billion market cap, and BioNTech sports a $79 billion valuation. Meanwhile, Novavax is positively cheap with its $17 billion market cap. The difference, of course, is that the mRNA biotechs have both of their COVID-19 vaccines on the market now, while Novavax is still waiting for its first Emergency Use Authorization. But when the government agencies start allowing Novavax to distribute its COVID-19 vaccine, the stock will really start to soar.

The majority of the world's population still has not been vaccinated. Novavax will have 2 billion doses of vaccine ready to distribute in 2022. And the biotech has multiple agreements for supplying locations around the world: 100 million doses for the U.S., 150 million doses for Japan, 200 million doses for Europe, and over 1 billion doses for the developing world. 

The U.S. paid $1.3 billion in advance to secure its 100 million doses of the company's experimental vaccine. That works out to $13 a dose. While the dollar amounts of the various purchase agreements are undisclosed, Japan and Europe will likely pay a higher dollar amount, while the developing world agreements will be discounted. It's entirely possible that Novavax's revenue next year will be higher than its market cap today.

I'm expecting Novavax shares to spike higher as its vaccine starts receiving authorization around the world in the fourth quarter. Novavax's vaccine candidate will be popular both as a booster shot and as an initial vaccine for the majority of the world who are unvaccinated. And Novavax is leading in the race to combine the COVID-19 vaccine with a flu vaccine. The company just kicked off a combo trial in Australia involving 640 people who have been vaccinated against both diseases with a single shot.

2. Sorrento Therapeutics: Don't sleep on this name

George Budwell (Sorrento Therapeutics): The clinical-stage biotech Sorrento Therapeutics rose to prominence last year thanks to its impressive lineup of experimental COVID-19 diagnostics and biologic therapies. The biotech's stock, in fact, gained a whopping 144% from January 2020 to March 2021 mostly because of its broad spectrum of COVID-19 vaccine candidates. Sorrento's shares, however, have now lost almost a quarter of their value over the past 180 days. Investors have apparently moved on to greener pastures, given the company's inability to bring even one of its various COVID-19 vaccine candidates to market in the United States. 

The core issue is that multiple biopharmas have been successful at developing and subsequently marketing COVID-19 vaccines, tests, and therapeutic antibodies in key markets like the U.S. and European Union over the last few months. Meanwhile, Sorrento is still on the hunt for its first major regulatory win. What's important for potential investors to understand, though, is that the pandemic is far from over. COVID-19 is highly likely to morph into a seasonal respiratory ailment. As such, investors shouldn't necessarily write off latecomers such as Sorrento. Eventually, the company could realize a healthy revenue stream from a COVID-19 diagnostic and/or therapeutic. 

It is entirely possible that Sorrento could garner multiple regulatory approvals for its COVID-19 vaccine candidates in the U.S. within the next calendar year, which would be a major boon for its stock. That said, this mid-cap biotech stock will surely remain on the volatile side until the company lands a Food and Drug Administration approval within the COVID-19 space. Invest accordingly.  

3. InMode stock will spike as the world reopens

Patrick Bafuma (InMode): As the world opens back up and people feel more comfortable gathering, the aesthetics market is sure to heat up. That's why my pick for a COVID-19 vaccine stock to double is InMode, the self-proclaimed leading global provider of innovative, minimally invasive aesthetic and wellness solutions, with strong brand recognition.

Using a razor-and-blades model, the company markets a medical device system and associated consumables that provide an energy source for body contouring. Utilized by multiple medical specialists, including plastic surgeons, dermatologists, gynecologists, ENTs, and ophthalmologists, InMode claims its procedures are longer lasting than laser treatment and less invasive than typical body sculpting procedures like liposuction.

And this $5.2 billion aesthetics company is firing on all cylinders. In the most recent quarter, InMode reported record revenue of $87.3 million, representing an increase of 184% compared to the second quarter of 2020. Total second-quarter sales outside of the U.S. were $30.9 million, more than triple what it reported during the same period last year. This torrid international growth represented 35% of its total revenue compared to 22% of its total revenue in Q2 2020. Currently operating in 68 countries, the company enjoys a massive runway for continued growth. 

As the world slowly returns to normal, consumers are seeking out treatments that they had delayed due to COVID-19. "Our demand is strong," chief medical officer Spero Theodorou noted on the last conference call. "It's solid all the way into September. Waiting lists ... (are) about a month out."

Theodorou went on to say, "Over one-third of the new patients coming in have never had (any aesthetics procedure) done before." This indicates that InMode has expanded the body contouring market, which had already reached $6.2 billion worldwide in 2020 despite the COVID-19 pandemic. This market is expected to grow at a compound annual growth rate of 7.2% into 2026, so there is plenty of room to run for InMode.

With many of us either in the house or masked up since March 2020, I expect continued growth for this aesthetics device maker as COVID-19 wanes. Despite InMode already being up over 180% since the start of 2021, the company has a huge runway, and its razor-and-blades business model continues to be an effective positioning strategy. InMode is already profitable with adjusted diluted earnings per share in Q2 coming in at $1.02 compared to $0.24 per diluted share for the same quarter of 2020. InMode looks like it's shaping up to double its share price again.