The coronavirus has claimed over 1,000 lives and infected more than 40,000 people, most of them in China, since the outbreak started in December. The SARS outbreak, by comparison, claimed nearly 800 lives in an eight-month period between 2002 and 2003.

The outbreak (thought to have originated in Wuhan, China) is sending shockwaves through China's economy, which is already growing at its slowest pace in three decades, as well as affecting American companies that rely on the country's supply chain and consumers.

I recently discussed the impact of the coronavirus on Chinese companies. Today, I'll highlight three American tech companies that could also be hit by the ongoing outbreak.

A row of dice spelling out "Coronavirus".

Image source: Getty Images.

1. Apple

Apple (AAPL 0.98%) generated 61% of its revenue from iPhones last quarter. That's a big problem for two reasons: Apple's top contract manufacturer Foxconn (FXCNF -7.87%) assembles its iPhones in China, and customers in China accounted for 15% of Apple's sales last quarter.

Apple temporarily closed its stores and offices in mainland China from Feb. 1 to Feb. 9 as a precautionary measure. Foxconn extended its Chinese New Year vacation by 10 days to Feb. 10, and only brought back about 10% of its workforce to restart work at its Zhengzhou and Shenzhen plants, according to Reuters.

Foxconn produces the iPhone 11 and the cheaper iPhone SE2 (iPhone 9) in Zhengzhou, while its Shenzhen plant develops Apple's upcoming 2020 iPhones. It's unclear when Foxconn will restart its other factories, but a recent Nikkei report claimed that there was still a "high risk" of coronavirus infection at most of its plants.

TF International Securities analyst Ming Chi-Kuo recently reduced his iPhone shipment forecast for the first calendar quarter by 10% to account for the outbreak, and he noted that smartphone shipments plunged 50%-60% annually during the Chinese New Year holiday, which indicates that Apple's iPhone shipments and overall revenue growth in China could decelerate significantly over the next few quarters.

2. Qualcomm

Qualcomm (QCOM 0.93%) generated 48% of its revenue from China last year. The chipmaker was already facing major headwinds in its top market -- including slowing smartphone sales, competition from first-party chipmakers, an unresolved licensing dispute with Huawei, and the trade war forcing Chinese OEMs to ditch American components -- when the coronavirus outbreak started.

Qualcomm's recent first-quarter report beat analysts' estimates on the top and bottom lines, but a few grim comments about the coronavirus sparked a post-earnings sell-off.

A businessman uses a smartphone.

Image source: Getty Images.

During the conference call, CFO Akash Palkhiwala warned of "significant uncertainty" regarding the outbreak's impact on Qualcomm's supply chain and handset demand. Palkhiwala also widened the lower end of its second-quarter EPS guidance by a nickel, from $0.85-$0.95 to $0.80-$0.95, which translates to a 21%-33% decline from a year earlier.

The reduction was minor, but management's uncertain tone regarding the outbreak's impact on its supply chain, along with its unresolved problems in China, indicate that investors should brace for more earnings pressure throughout the year.

3. Qorvo

Qorvo (QRVO 2.89%) mainly sells radio frequency (RF) and Wi-Fi modules. Its top customers are Apple and Huawei, which accounted for 32% and 13% of its revenue in fiscal 2019, respectively. It also generated 34% of its revenue from China in the first nine months of fiscal 2020 and cited content share gains in Chinese handsets as a key catalyst for its future growth.

Qorvo's heavy customer concentration and exposure to China indicates that analysts' forecasts for 7% revenue growth and 8% earnings growth next year could be too optimistic. Citi analyst Atif Malik recently reduced his share price target on Qorvo from $120 to $117, citing "negative demand" and the coronavirus outbreak's disruption of China's smartphone supply chain.

During last quarter's conference call, CFO Mark Murphy declared that Qorvo's near-term outlook remained "healthy," but that it was "keeping a close eye" on the coronavirus outbreak with "extensive checks on the supply chain." That uncertain outlook indicates that Qorvo's growth could decelerate significantly if the outbreak worsens.