A shortage of a testing component is hobbling the U.S. battle against COVID-19 as the number of confirmed coronavirus cases rises.

Earlier testing was marred by problems that produced potentially inaccurate results. As U.S. testing ramps up, some labs have run short on the kits and components needed to determine whether samples taken from ailing patients confirm the presence of the novel coronavirus.

The number of confirmed COVID-19 cases in the USA rose to 1,050, and there have been 29 deaths, as of Wednesday morning, according to Johns Hopkins University.

In some cases, the shortage prompted lab personnel to borrow components from colleagues using similar kits for testing unrelated to COVID-19, said Marc Lipsitch, a Harvard University epidemiologist. The extent of the problem could not immediately be determined.

"What we need is a lot more testing, right now," Lipsitch said, but testing kits and components "are in very short supply."

Some of the testing components are manufactured by Qiagen, a multinational leader in molecular testing headquartered in Germany. Responding to spiking demand for its products, the company increased production to three shifts a day, seven days a week, at plants in Germany and Spain.

"This now is an unprecedented situation," said Qiagen corporate spokesman Thomas Theuringer. "Demand is exploding, especially in the United States ... and this is stretching our capacity."

The Centers for Disease Control and Prevention is looking into the shortage, Director Robert Redfield told Politico on Tuesday. “I’m confident of the actual test that we have, but as people begin to operationalize the test, they realize there’s other things they need," he said.

Michael Mina, a Harvard professor of epidemiology, tweeted Monday that the testing components are critical.

The shortage results in part from the increase in COVID-19 testing across the USA after a slow start due to problems with testing kits from the CDC. State and local health officials responded by calling on the federal government for authorization to use tests they developed. That began in many places over the past week.

Testing is done by health departments and clinical diagnostic laboratory giants such as Quest Diagnostics and Laboratory Corp. of America.

Testing for coronavirus typically uses reagents, which are chemical substances used in laboratory analyses. The reagents extract, purify and stabilize RNA, or ribonucleic acid, in samples taken from patients suspected of having COVID-19.

That's the first step in confirming or ruling out a tentative diagnosis. Qiagen says it leads the world in this type of testing.

Testing demand has led to a shortage of reagents for the RNA extraction process, said Dr. Eric Blank, the chief program officer for the Association of Public Health Laboratories, which represents state and local governmental health laboratories in the USA and responds to disease outbreaks.

"We are now in the phase of the response where demand for testing is greater than the tests available, even when the private/commercial sector is doing testing," Blank said in an email.

The Society for Microbiology posted a warning on its website that the shortage could delay COVID-19 testing.

"We are deeply concerned that as the number of tests increases dramatically over the coming weeks, clinical labs will be unable to deploy them without these critical components," the microbiology group said.

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Along with increasing its production, Qiagen hired more employees and increased manufacturing at a facility in Germantown, Maryland.

"Given our ongoing supply to the United States," Theuringer said, "we are now working directly with the customers to understand their flexibility and specific needs in order to be able to ensure broad availability of our products."