Will the stock market continue to soar in 2021? Or will another crash be right around the corner? No one knows what will happen for sure. For some stocks, though, what the overall market does won't matter very much.

In particular, biotech stocks can be practically bulletproof. Their fortunes usually hinge on pipeline developments that have nothing to do with what's going on in the rest of the world. Many biotechs have products on the market that are so critical for patients that sales will keep growing even if the economy tanks.

But which stocks are good picks? Here are three top biotech stocks to buy right now.

Test tubes with ascending levels of green liquid in each tube and a green arrow sloping upward in the background

Image source: Getty Images.

1. Vertex Pharmaceuticals

I genuinely think that Vertex Pharmaceuticals (NASDAQ:VRTX) is the best biotech stock on the market. The company is rolling in dough. Vertex is on track to generate sales of at least $6 billion this year, more than 40% higher than the $4.2 billion reported for 2019. Its tremendous profits continue to add to its huge cash stockpile of over $6 billion.

Vertex's theme song could be MC Hammer's "U Can't Touch This." The reality is that no other company can touch its dominance in the cystic fibrosis (CF) market. There are currently four approved drugs in the U.S. and Europe that treat the underlying cause of CF. Vertex developed and markets all of them. No other drugmaker has a CF candidate beyond phase 2 clinical testing.

The great news for Vertex is that its latest blockbuster CF drug, Trikafta/Kaftrio, has just begun to pick up momentum in Europe. I look for solid sales growth over the next few years as the company secures additional reimbursement deals in key European markets.

I'm also optimistic about Vertex's pipeline prospects. The biotech did have a setback this year for one candidate targeting rare genetic disease alpha-1 antitrypsin deficiency (AATD). However, Vertex has another AATD candidate in phase 2 testing and a promising program targeting genetic kidney diseases.

Vertex and CRISPR Therapeutics could have a cure potentially on the way for rare blood disorders sickle cell disease and beta-thalassemia with CTX001. The gene-editing therapy is currently in early-stage testing with promising initial results.

2. Exelixis

It's surprising to me that Exelixis (NASDAQ:EXEL) isn't bigger than its current market cap of a little over $6 billion. The biotech could generate close to $950 million in revenue this year. More sales growth should be on the way in 2021 and beyond.

Exelixis' flagship product Cabometyx is currently approved by the U.S. Food and Drug Administration (FDA) as a second-line treatment for renal cell carcinoma (RCC) and hepatocellular carcinoma (HCC). RCC is the most common form of kidney cancer, while HCC is the most common form of liver cancer. 

However, the biotech hopes to receive FDA approval early next year for a combo of Cabometyx and Bristol Myers Squibb's immunotherapy Opdivo as a first-line RCC therapy. This could open up a much larger market opportunity. Exelixis is also working with Roche to evaluate a combination of Cabometyx with Tecentriq in late-stage studies targeting several types of cancer, including RCC and non-small cell lung cancer.

Thanks to the success of Cabometyx, Exelixis has steadily built up its cash position, which totaled $1.5 billion as of Sept. 30, 2020. The company is using its newfound wealth to expand its pipeline, recently licensing programs from Iconic Therapeutics and Aurigene, a subsidiary of Dr. Reddy's Laboratories. I think Exelixis' strategy of building its pipeline is a good one that could pay off nicely over the long run.

3. Novavax

Novavax (NASDAQ:NVAX) is listed last on the list because it doesn't yet have an approved product on the market and is therefore a riskier pick than Vertex or Exelixis. However, I believe that Novavax just might be the biggest winner of the three biotech stocks over the next few years.

The center of attention for Novavax is its experimental COVID-19 vaccine NVX-CoV2373. Novavax is currently evaluating the vaccine in a late-stage study in the U.K. It hopes to soon begin late-stage testing in the U.S. and Mexico, as well.

So far, the company has lined up supply deals with the U.S., U.K., Australia, Canada, and New Zealand totaling nearly 287 million doses. Novavax also teamed up with other companies to sell NVX-CoV2373 in India, Japan, South Korea, and other low- and middle-income countries. Bernstein analyst Ronny Gal projects that the biotech will rake in $3.8 billion in sales from its COVID vaccine next year.

In addition, Novavax hopes to win FDA approval for flu vaccine NanoFlu. The nanoparticle-based flu vaccine handily outperformed market leader FluZone Quadrivalent in a late-stage study completed earlier this year. With two potential blockbuster vaccines on the way and a market cap around $8 billion, Novavax could skyrocket in 2021.

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.