Although the coronavirus crisis is far from over, it has already transformed the way healthcare players operate. Some companies have seen record demand for their essential medicines, while others have only recently seen their revenues rebound after shutdowns and stay-at-home orders wreaked havoc on their business.

In spite of the ups and downs of the year, the timing has actually never been better for investors to get into the market. The top healthcare stocks in the S&P 500 index have returned between 23% and 96% year to date, making the benchmark's 6.6% rally look pretty measly.

In a market where winners keep winning and losers keep losing, the best way to ensure the safety of your capital is to buy stocks that are proven performers with future growth potential. Here are the 10 biggest healthcare winners in the S&P 500 index so far this year, and the reasons why they will enrich your portfolio for years to come.

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1. DexCom

DexCom (DXCM -1.05%) creates continuous glucose monitoring systems that can transform how patients with diabetes manage their condition. To date, the company has captured more than 20% of the type 2 diabetes patient market in the U.S. In its quarter ended June 30, the company's revenue grew by 34% to $451.8 million from the second quarter of 2019. The stock is currently trading at $427, up a whopping 95% year to date.

2. Abiomed

Abiomed (ABMD) is the distributor and manufacturer of Impella, the world's smallest heart pump. The company's product is protected by over 884 patents, with an additional 759 pending. The U.S. Food and Drug Administration (FDA) recently approved Impella for the treatment of certain types of heart failure in patients with COVID-19, which should create strong demand for the device in the near future. Abiomed has no debt and about $600 million in cash on its balance sheet. The company's stock has been handsomely rewarded for this performance, up almost 80% so far this year.

3. West Pharmaceutical Services

West Pharmaceutical Services (WST 2.10%) plays a critical role in producing injectable drugs and drug delivery systems. The company is poised to package billions of doses of COVID-19 vaccines as they clear clinical trials. Demand for its services has increased significantly due to the pandemic, and West Pharmaceutical Services is now expecting up to $4.25 earnings per share by the end of the year, which is up from $3.62 in the previous quarter. The stock is trading at 11 times sales, showing that investors are expecting a lot of growth out of the coronavirus vaccine opportunity.

4. Regeneron

A notable entry on this list is large-cap biotech Regeneron (REGN 1.69%), which markets a diverse portfolio of biologics. The drug Eylea, which is used to treat retinal diseases, generates about $1.75 billion in revenue per quarter. Newly commercialized products, such as Dupixent, used in the treatment of specific allergies, and Libtayo, a cancer treatment drug, generated a stunning $1 billion and $80 million in sales just a few years after their approvals.

Regeneron has accumulated about $5.7 billion in cash and investments to offset its $1.5 billion in debt. Year to date, the company's stock has jumped from about $370 to $606. For all its impressive growth, the company is trading at just nine times sales.  

5. IDEXX Laboratories 

As one of the world's largest providers of veterinary and livestock products, IDEXX Laboratories' (IDXX 0.87%) financial results have captivated investors. During the second quarter of 2020, the company's annual earnings per share increased by 23% to $1.72. In June, its diagnostics business saw 30% growth compared to May. The company's share price is up 47% this year to $383. IDEXX should continue to benefit from an impressive long-term trend in pet spending; U.S. pet expenditures have gone up every single year for the past 25 years.

6. Bio-Rad Laboratories 

Bio-Rad Laboratories (BIO -0.14%) is a leader in life science research and clinical diagnostics development. Last quarter, the company recorded $536.9 million in revenue and $48.3 million in earnings from strong growth in sales from its COVID-19 and medical tests. The company is in a superb financial position, with $1.03 billion in cash and investments, which is enough to offset its $438.7 million in debt. At seven times price-to-sales, this is a good deal for investors looking for growth at a reasonable price.

7. Hologic 

Women's health and technology company Hologic (HOLX 0.36%) stock has been on a tear this year due to the popularity of its COVID-19 diagnostic tests. There are now 13 million of the company's tests utilized per week, accounting for more than 25% of the total COVID-19 testing market. Hologic can manufacture up to one million tests per week, which helps the company generate about $324 million per quarter in revenue. At $66.11, or 27 times price-to-sales, the company's stock may have more room to appreciate based on continued demand for coronavirus testing.

8. Danaher

Medical conglomerate Danaher (DHR 0.44%) received an uptick in orders for its medical instruments as part of the efforts to fight the pandemic. Overall revenue grew by 3.5% annually to $5.3 billion in the second quarter of 2020. Danaher also netted $1.44 in earnings per share, representing a 30% improvement from Q2 2019. Year to date, the company's share price has grown from around $155 to $207.57.

9. Thermo Fisher Scientific

Thermo Fisher Scientific (TMO 0.75%) is a life science company providing scientific instruments, reagents, consumables, and various software and services. During Q2 2020, the company's revenue increased by 10% year over year to $6.92 billion. It grew its earnings per share to $3.89, an increase of 28%. The pandemic continues to help boost demand for the company's services by about $1.3 billion per quarter. The stock is worth $422.29 per share, up about 30% from the beginning of 2020.

BIO Chart

BIO data by YCharts

10. Vertex Pharmaceuticals 

Finally, biotech Vertex Pharmaceuticals (VRTX 0.78%) has seen its revenue and bottom line skyrocket since its triple combination therapy, Trikafta, came to market as a treatment of cystic fibrosis patients with a critical gene mutation. The drug is likely to capture up to 90% of the global cystic fibrosis market. During Q2 2020, the company's revenue increased by 62% year over year to $1.52 billion. Meanwhile, its net income more than doubled to $1.36 billion compared to the same period last year. Vertex Pharmaceuticals is trading at $272.35, up 23.5% this year.