The widening coronavirus outbreak has been weighing on medical device companies amid concern the current crisis will interrupt use or orders of their products.

Here, let's talk about two companies -- one that is seeing an impact and one that hasn't so far. Do I like one better than the other? No. Both are trading at bargain prices and make great long-term investments due to their growth prospects.

1. Boston Scientific

Boston Scientific (NYSE:BSX), a maker of devices including stents and catheters, is trading near its lowest ever in relation to earnings and at its lowest since 2015 in relation to book value.

The stock has dropped 32% so far this year and may see further declines after withdrawing guidance for the first quarter and 2020 full year. The company made the announcement in a filing on March 30, citing the postponement of elective medical procedures as well as other disruptions linked to the outbreak. More details will come during the April 29 earnings call. In February, Boston Scientific already estimated the coronavirus in China could have a $10 million to $40 million negative impact on its sales in the first quarter. Though none of this is very positive and it's unlikely the company will have a glowing year, let's have a look farther into the future.

An investor looks at a declining stock chart on his tablet.

Image source: Getty Images.

The U.S. Food and Drug Administration recently cleared Boston Scientific's Exalt Model D duodenoscope, and the company was preparing to launch the device in the first quarter. Though it's possible the launch won't happen according to the original timeline, that doesn't hurt my optimism. Duodenoscopes are used in endoscopic retrograde cholangiopancreatography, or ERCP, a procedure to explore pancreatic and bile ducts and treat related conditions. ERCP is performed 1.5 million times globally every year, representing a big opportunity for Exalt-D. What makes Exalt-D different from the competition is it is the only FDA-cleared single-use duodenoscope. That means less chance of patient exposure to disease-causing pathogens. CEO Mike Mahoney even said in the recent earnings conference call that Exalt-D could be a blockbuster.

2. Illumina

DNA sequencing giant Illumina (NASDAQ:ILMN) has some good news. The company so far hasn't experienced notable supply chain or operation delays due to the outbreak. At the same time, Illumina is trading near its lowest in two years in relation to earnings and at its lowest in relation to book value since 2016. The shares are down 18% this year.

One of the reasons I like Illumina is its leadership position in a growing market. According to Morningstar, Illumina holds a 70% share of the sequencing market. The global next-generation sequencing market is expected to grow at a compound annual growth rate of more than 11% to reach $23.7 billion by 2027, according to a report by Grand View Research. Illumina surpassed analysts' estimates for earnings per share in the past four quarters, and sales and profit have gained over the past two years.

In recent news, Illumina has partnered with IDbyDNA, using the company's platform for laboratory workflow management and analysis in its next-generation sequencing systems for infectious diseases. Work will start with COVID-19, the illness caused by the novel coronavirus. The system will allow researchers to identify the presence of the virus and decode the genetic components of different viral strains. As a result, it may play an important role in the development of better tests. Most interesting for the long term, however, is Illumina's presence in the oncology market. In its last earnings call, Illumina said oncology makes up 20% of its total sequencing consumables, which include items like test kits. The oncology segment grew faster in 2019 than total clinical consumables, according to the company.

A buying opportunity?

Investors may use weakness in Boston Scientific or Illumina as a buying opportunity. It's possible there will be additional low points in the coming weeks as the coronavirus outbreak unfolds, and as we've seen, that could even weigh on shares of companies like Illumina that so far haven't taken a direct hit. Still, an investment now has potential to pay off later. Boston Scientific and Illumina are shares to hold onto for a while, to benefit from product sales in the years to come.

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.