In spite of the March market crash, the year has been decent for biotech stocks. The iShares Nasdaq Biotechnology ETF (NASDAQ:IBB) is up 11% since the start of 2020. That's compared to the S&P 500's 6.3% gain. The industry's work in potential coronavirus vaccines and therapies have lifted some stocks. But even those that aren't involved in coronavirus research offer growth opportunities due to strong products.

Here, I'll talk about three biotech stocks I would buy right now -- and keep for the long term. Vertex Pharmaceuticals (NASDAQ:VRTX) is trading at a bargain considering its product portfolio and earnings to come. Amgen (NASDAQ:AMGN) is beginning a new phase of growth. And finally, for the most aggressive investors, Novavax (NASDAQ:NVAX) represents an opportunity to bet on coronavirus and flu vaccine candidates. Let's take a closer look.

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Vertex Pharmaceuticals

Vertex shares are trading at about 21 times estimated earnings, down from more than 30 times forward earnings back in July. The company's valuation by this measure and the stock price are both close to the levels they reached during the March crash.

VRTX Chart

VRTX data by YCharts

The reason? Vertex's shares sank 21% in one trading session after the company said it would discontinue development of VX-814 for alpha-1 antitrypsin deficiency (AATD). AATD is a genetic disorder that leads to lung and liver problems.

There are three reasons why I consider the reaction overdone and favor buying shares now. Vertex also said the phase 2 trial of VX-864, a structurally different candidate for AATD, continues. So, this doesn't represent an end to an entire treatment area. Second, the company has about a dozen product candidates in clinical trials for indications including blood disorders, pain, and cystic fibrosis.

And speaking of cystic fibrosis, that's the third reason to buy Vertex. The company is a market leader and continues to grow. Last year, Vertex launched Trikafta, a treatment with the potential to address 90% of cystic fibrosis patients. Trikafta already generated $918 million in sales in the most recent quarter.

Amgen

Amgen saw annual revenue stagnate over the past couple of years as competition hurt sales of older products like bone-marrow stimulant Neulasta. But newer products are reason to be optimistic about a fresh phase of growth.

For example, sales of psoriasis treatment Otezla have been increasing since Amgen acquired it last November. The drug generated $479 million in its first full quarter. And in the second quarter, it brought in $561 million in revenue for a 14% gain compared with the same period a year earlier. The global psoriasis drug market, at a 9.4% compound annual growth rate, is expected to reach $21 billion by 2022, according to Grand View Research. Otezla's advantage is it's a pill, making it more convenient than an injection or cream.

Cholesterol drug, Repatha, is another high-growth product for Amgen. Repatha's sales climbed 32% in the second quarter, and its share of new patient prescriptions stood at 80%. Amgen also has a hefty pipeline, including more than 20 phase 3 programs.

Novavax

Novavax is one of the players in the coronavirus vaccine race. But that isn't the main reason why I like the stock. What first drew my attention to this company was its flu vaccine candidate -- NanoFlu. It met all primary endpoints in a phase 3 trial earlier this year. Soon, Novavax will submit the investigational product to the U.S. Food and Drug Administration for approval. Considering trial results, I'm optimistic.

Now, let's talk about the company's coronavirus vaccine candidate. Interim results have been positive, but from a timeline perspective, Novavax is unlikely to reach the finish line first. The company launched a phase 3 trial in late September, but rivals such as Moderna entered phase 3 several weeks earlier. That's OK. Here's what is really exciting about Novavax right now: The company plans to explore a combined flu/coronavirus vaccine. Any resulting product would be used post-pandemic. No one likes getting shots. So, the idea of a two-in-one vaccine could be a game-changer.

Novavax is a stock to consider only if you're an aggressive investor with high-risk tolerance. Why is it risky? Because this company doesn't yet have products on the market, and the shares are highly sensitive to coronavirus vaccine news. For example, the stock has gained more than 2,000% so far this year thanks to the company's coronavirus program. If there's any bad news on the horizon, a decline could be just as spectacular. That means more cautious investors should probably watch from the sidelines or take a very small position in shares of this biotech stock.