Investors need a bevy of high-growth stocks as part of every well-rounded biotech portfolio, and the market's furor surrounding the prospect of a COVID-19 vaccine creates the perfect conditions for those seeking returns in the biotech space. 

Thanks to the market's excitement about the vaccine development activities of these three companies, each has exhibited stunning growth in the first half of this year, making them attractive options for investors seeking profit.

Three scientists work in a laboratory.

Image source: Getty Images.

Inovio Pharmaceuticals

Before the pandemic, Inovio Pharmaceuticals (NASDAQ:INO) was a typical biotech stock, with its growth dependent entirely on favorable clinical trial outcomes. Inovio ended last year with a market cap of $335 million and a scant few million in cash -- hardly a major contender in the vaccine development market. Now, after a salvo of positive news regarding its early-phase COVID-19 candidate, the company has a market cap of $3.7 billion and $270 million in cash, and its stock price is up more than 650% from the start of the year.

The impressive market-cap increase of more than 1,060% also accounts for a pair of at-the-market (ATM) stock sales of $121.7 million and $208.2 million in the spring. These dilutive actions could have dismayed investors, if not for the stock's rapid and speculative expansion in the same period.

Inovio has a handful of vaccine-related products in the works that may deliver future growth. Between the imminent publication of the phase 1 trial results for its U.S. government-funded vaccine delivery device, reports of progress in its phase 2 COVID-19 candidate, and advancement in its non-COVID pipeline programs, the rest of the year will be a good time to consider an investment in Inovio.

If its vaccine delivery device proves to be safe and effective in clinical trials, it's reasonable to assume that the government will want to purchase a large volume to enable inoculation of its employees and servicemembers.

Novavax

With its stock up by more than 550% this year, Novavax (NASDAQ:NVAX) has all the hallmarks of an investment that could make investors rich. Like Innovio, Novavax doesn't yet have a product approved for sale, but it does have a COVID-19 vaccine candidate that appears promising. Its candidate uses a proprietary adjuvant (an agent that boosts immune response), Matrix-M. The company claims its boost to immunogenicity will reduce the effective dose required, thereby making mass-scale manufacturing more economical.

In early July, Novavax received $1.6 billion in funding from the U.S. government's accelerator program, Operation Warp Speed, suggesting that its candidate could also be one of the most advanced in the development process. 

Investors should expect that the company's stock will jump upward again if it reports favorable results in its COVID-19 candidate's combined phase 1/2 trial, scheduled for later in July. However, even if its COVID-19 attempt doesn't pan out, the company still has a bevy of other late-stage projects, meaning that it will still be a worthwhile growth stock in the long-term, if not a millionaire-maker.

SPY Chart

SPY data by YCharts

Vaxart

Vaxart (NASDAQ:VXRT) has grown more rapidly than both Inovio and Novavax, exciting investors with its impressive expansion of about 4,000% this year as a result of its unique COVID-19 vaccine tablet. The tablet can be manufactured as a vaccine against several different diseases, and unlike liquid vaccines, the oral tablets are shelf-stable, require no healthcare worker support to administer, and need none of the typical vaccination-adjacent goods like syringes or sterile wipes, making them significantly more attractive to healthcare systems everywhere. This means that even if its COVID-19 candidate isn't effective, Vaxart is still sitting on a highly valuable technology that it could use to drive revenues with its other programs.

On July 13, it raised $90 million by selling 11.2 million shares of stock, suggesting that it is preparing to make major investments in its clinical development pipeline or its manufacturing capacity, and the stock soared more than 50% as a result. Like Novavax, Vaxart was chosen to participate in Operation Warp Speed, but for a preclinical project that didn't result in as much direct funding. 

Vaxart's market cap is still only $778 million, though that's a massive expansion from the $11 million it exhibited a year ago. If leadership continues to build new collaborations with prospective vaccine manufacturers while also reporting favorable results in the course of its candidate's clinical trials, as it has so far this year, it may well be the single most effective COVID-19 stock for investors looking for riches.