Last week, the stock market experienced its worst week since the financial crash of 2008. And while the current week started on a more positive note, uncertainty will remain as long as the COVID-19 epidemic persists. With COVID-19 showing up in more and more countries outside of China -- and the number of cases increasing worldwide -- no one knows for sure when things will calm down.

But the worst thing investors can do at this point is panic. There are lots of companies with long-term prospects that will remain intact despite the recent developments surrounding COVID-19. In particular, here are two biotech stocks I think investors should consider buying, regardless of the coronavirus market correction: Vertex Pharmaceuticals (VRTX 0.38%) and Global Blood Therapeutics (GBT).

The leader in the cystic fibrosis market

The best reason to buy shares of Vertex Pharmaceuticals is the company's monopoly on the market for treatments for cystic fibrosis (CF). This rare genetic condition causes damage to the lungs and the digestive system, often shortening the patient's lifespan. Just 10 years ago, there were no treatments that addressed the underlying causes of CF approved by the U.S. Food and Drug Administration (FDA), but Vertex had several of its drugs aimed directly at the underlying causes of CF approved over the previous decade. The company's most recent approval is particularly noteworthy. 

Doctor surrounded by DNA strands.

Image source: Getty Images.

In October, the FDA approved Vertex's Trikafta, a combination of drugs that treats the underlying causes of CF. Thanks to this approval, the number of CF patients eligible for Vertex's products increased from 44,000 to 68,000. For context, there are an estimated 75,000 patients with CF in the U.S., Europe, and Australia. 

Vertex's revenue has been growing at a good clip in recent years. During the fourth quarter, the company recorded a net product revenue based on Generally Accepted Accounting Principles (GAAP) of $1.4 billion, 63% higher than the year-ago period. For the full year, Vertex recorded a GAAP net revenue of $4.2 billion, 37% higher than it was during the previous fiscal year. The company's revenue growth likely won't stop anytime soon. 

Furthermore, Vertex has other products in its pipeline, some of which are being investigated as treatments for CF. Vertex is targeting other conditions as well. The company is currently developing a promising product -- called CTX001 -- that could potentially treat two blood disorders, namely sickle cell disease (SCD) and transfusion-dependent beta-thalassemia (TDT). Vertex is developing CTX001 in collaboration with CRISPR Therapeutics (CRSP 3.92%).

This partnership began in 2015 when the two companies teamed up to develop new treatments for genetic diseases. Back then, CRISPR Therapeutics received an upfront payment of $105 million from Vertex, which included $30 million in equity investment and $75 million in cash. Thanks to this collaboration -- and others -- Vertex could find more exciting products to market and reap the benefits for many years to come, which makes it a stock worth considering. 

Tackling the underlying cause of sickle cell disease

Suggesting an investment in Global Blood Therapeutics might initially be met with skepticism. After all, this is a company that recorded a measly $2.1 million in net sales last year, along with a net loss of $266.8 million. However, Global Blood is worth consideration, and here's why. In November, the FDA approved Oxbryta, which is a treatment for SCD and, thus far, the only approved product Global Blood has on the market. 

Why is this approval a big deal? First, it is essential to understand the cause of SCD. Hemoglobin is a component of red blood cells that carries oxygen around the body. Due to a genetic mutation, the hemoglobin in patients with SCD changes shape and stiffens. This process interferes with the flow of blood and oxygen around the body, which can lead to severe complications.

Oxbryta is the first FDA-approved drug that directly targets the underlying cause of SCD by preventing the hemoglobin from changing shape. Given that there are an estimated 100,000 patients with SCD in the U.S. -- and millions more worldwide -- Oxbryta could rack up strong sales in the coming quarters. The recent approval also helps give more credence to Global Blood's mission, which is to "develop and deliver innovative treatments that provide hope to underserved patient communities." 

With that said, Global Blood has a tough road ahead. With its only drug on the market just recently gaining FDA approval, it could be a while before the company's financial results truly take off. Still, given its recently approved treatment for SCD, it is worth keeping an eye on this company.