(CNN) Panic over the novel coronavirus is hitting a fever pitch in the US. And despite repeated pleas from health officials not to purchase them, Americans can't stop snatching up masks and respirators.

The mask boom has prompted sellers to jack up prices and exploit demand. This has meant a shortage for medics who need them.

"We need to make sure those N95 masks are available for the doctors and nurses that are going to be taking care of individuals that have this illness," Centers for Disease Control and Prevention Director Robert Redfield said during a House Foreign Affairs hearing on Thursday.

"And it really does displease me, to find people going out, there is no role for these masks in the community."

Americans don't need masks. They buy them because they're scared

But medical workers who treat patients with novel coronavirus do need them. And, the CDC says, it's crucial that those supplies don't run out.

When it comes to hysteria and panic, though, reason takes a backseat.

"This is a psychological thing," Dr. William Schaffner, a professor of preventive medicine at the Vanderbilt University School of Medicine, told CNN. "The coronavirus is coming, and we feel rather helpless. By getting masks and wearing them, we move the locus of control somewhat to ourselves."

Overwhelming demand leads to price gouging

Demand for the masks is the highest its been in months. According to data provided to CNN by Helium 10, a software company that assists Amazon retailers, Amazon users have searched for the word "N95 mask" more than 862,000 times in the last 30 days. In December, users searched for the keyword a mere 4,500 times over 30 days.

And with overwhelming demand comes inevitable price gouging.

The top-selling mask product, a 100-pack of Universal 4533 sanitary dust masks, started selling at $8. The price eventually rose over $200, Helium 10 said.

Photos: A global coronavirus: Travel bans, face masks, and fear In this photo illustration, a woman sprays disinfectant onto her hands in Berlin, Germany, on February 26. As the novel coronavirus spreads across Asia, people have rushed to stock up on sanitation and cleaning products. In major cities like Hong Kong, stores sold out of hand sanitizer, toilet rolls, face masks, disinfecting wipes, and more. Hide Caption 1 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear Commuters in Beijing wear protective masks as they ride bikes and scooters across an intersection during rush hour on February 24. Nearly everyone in Beijing and across mainland China is wearing a protective mask outdoors, if they go out at all; some instead choose to stay home as much as possible, in line with the government's recommendation to self-quarantine and avoid public gatherings. Hide Caption 2 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A child is covered with a plastic bag before getting into a taxi in Beijing on February 13. Hide Caption 3 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A woman checks her son's forehead on January 27 in Wuhan, China. The coronavirus outbreak began in Wuhan, and the majority of cases in China remain concentrated in Hubei province, where Wuhan is the capital. Wuhan has been under lockdown since January 23, with movement halted in or out of the city, and public transport limited within. Hide Caption 4 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear Staff disinfect a room in Hotel Mikazuki, in Japan's Chiba Prefecture, where Japanese evacuees from Wuhan stayed. 197 Japanese citizens had been flown out of the Chinese city, and stayed at the hotel for two weeks. They went home on February 13 after all testing negative for the coronavirus. Foreign nationals from at least 30 countries were flown out of Wuhan and other regions of China in January, amid growing travel restrictions and border closures. Hide Caption 5 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear With governments worldwide advising citizens to avoid close physical contact for fears of spreading the virus, even religious services have had to adjust. Catholic devotees in Paranaque city, the Philippines, line up on February 26 to have their head sprinkled with ash during Ash Wednesday services -- instead of the usual practice of having the ash rubbed in. Hide Caption 6 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A worker from the Korea Pest Control Association, wearing protective gear, sprays disinfectant at a market in Seoul on February 24. South Korea has seen a spike in numbers as a new outbreak spreads across the country. There are now more than 1,500 cases nationwide, many of which are linked to a religious group in the south of the country. Hide Caption 7 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A Chinese man wears a protective mask, goggles and coat on a nearly empty street on January 26 in Beijing, China. The outbreak hit during Chinese New Year -- China's busiest annual travel season. This year, celebrations were canceled, travel restrictions were implemented, and the typical festive atmosphere was replaced by one of fear and caution. Hide Caption 8 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear Workers spray disinfectant inside a toilet at a bus depot in Seoul, South Korea, on February 24. The majority of cases in South Korea have taken place in the southern city of Daegu, but infections have also spread to other places like Busan -- the country's second most populous city. Hide Caption 9 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A worker cleans a metro train in Tehran, Iran, on February 26. An outbreak in Iran has seen the country's coronavirus numbers spike; it now has more than 140 cases and 22 deaths.

Many other Middle Eastern countries have imposed travel restrictions and strict emergency measures, including closing borders with Iran. Within a week of the Iran outbreak, a number of nearby countries reported their first cases, including Afghanistan, Bahrain, Oman, Lebanon, and more. Hide Caption 10 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear Workers clean a gate at Hong Kong's High Speed Rail Station on January 29. The city's government announced it will deny entry for travelers who has been to China's Hubei province, the epicenter of the outbreak, except for local residents. Hong Kong has also closed many of its border crossings with mainland China, amid calls from residents for more stringent measures. Hide Caption 11 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A worker disinfecting a market in Seoul, South Korea, on February 24. South Korea is now the largest outbreak outside China. Hide Caption 12 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A worker wears disposable latex gloves while serving food at a cafe in Milan, Italy, on February 24. Italy is now the largest outbreak outside Asia, and is at the heart of the European outbreak. Since Italy's outbreak, the virus has spread to many other nearby countries; Norway, Denmark, Austria, Romania, Georgia, and North Macedonia all reported their first cases within a week. Hide Caption 13 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear Temporary "mothers" Zhang Xiaoyan and Wang Simei feed the 2-month-old child of a coronavirus patient in China's Anqing City on February 20. The baby's mother was confirmed with coronavirus after all other adult members of her family were also infected -- leaving two children without caretakers. In response, six local nurses stepped in to act as the children's temporary "mothers." Hide Caption 14 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A traditional market in Seoul is disinfected on February 26. The South Korean government raised its coronavirus alert to the highest level, with confirmed case numbers continuing to rise. Hide Caption 15 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A worker at Manila's international airport cleaning chairs at the boarding area on February 23. The Philippines has three confirmed cases and one death from the coronavirus. The country has issued travel restrictions in response to the Asia outbreak; most recently, it announced a ban on travelers from the North Gyeongsang Province of South Korea, where numbers of cases have been climbing. Hide Caption 16 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A customer wearing a protective face mask and gloves reads a cleaning product label in a grocery store in Milan, Italy, on February 25. Italian authorities are now scrambling to respond to the outbreak, after the prime minister was forced to admit that a hospital had mishandled the region's first coronavirus case and had contributed to the virus' spread. Hide Caption 17 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear People wear face masks in Tokyo on February 23. Japan came under international scrutiny after the Diamond Princess cruise, docked in Yokohama, was placed under quarantine for weeks with infected passengers on board. Hide Caption 18 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear An airport employee scans people's body temperatures in Bolivia on February 26. Brazil reported its first case of the coronavirus that day -- the first case in Latin America. Other nearby countries are now attempting to block the possible spread of the virus. Hide Caption 19 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A medical staff member in the Wuhan Children's Hospital in Wuhan, China -- the epicenter of the coronavirus outbreak. At the isolation ward of infected children, many young patients were afraid of seeing the medical staff wrapped in protective suits. A nurse in the hospital came up with the idea of drawing cartoons on the protective suits and inviting children to color them, to make them feel more at ease. Hide Caption 20 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A man wearing a respiratory mask and gloves in Milan, Italy, on February 23. He is in Casalpusterlengo -- one of the ten small towns placed under lockdown as new coronavirus deaths sparked fears throughout the Lombardy region of Italy. The travel restrictions have effectively quarantined 100,000 people in the region. Hide Caption 21 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear Chinese children wear plastic bottles as makeshift homemade protection at the airport in Beijing on January 30. People in China aren't taking any chances. Apart from just face masks, they have turned to other ways to protect themselves from the virus in public, like wearing full-body plastic ponchos, shower caps, goggles, gloves, and more. Hide Caption 22 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear Sumo wrestlers in Osaka, Japan, on February 23. The Osaka Grand Sumo Tournament will start on March 8. But many other sporting events and major public gatherings have been canceled across Asia as the coronavirus spreads. There was speculation that the Tokyo 2020 Olympic Games could be canceled as well -- but organizers told CNN preparations for the Games were continuing as planned. Hide Caption 23 of 24 Photos: A global coronavirus: Travel bans, face masks, and fear A Chinese man is seen in the side mirror of his scooter as he wears a protective mask in Beijing on February 22. More than 780 million people across China -- nearly half the country's population -- are still under some kind of travel restriction. These restrictions range from complete lockdowns, to limited entry in and out of certain neighborhoods. Hide Caption 24 of 24

And even at that price, the product is selling. Or it was -- it's out of stock as of Friday.

Some products don't display a box where users can click to purchase it. Helium 10 said this means Amazon removed the sellers because they'd rapidly increased their prices.

In a statement to CNN, an Amazon spokesperson said removal is part of its company policy to discourage price-gouging sellers.

"Sellers set their own product prices in our store and we have policies to help ensure sellers are pricing products competitively," the spokesperson said. "We actively monitor our stores and remove offers that violate our policies."

But that doesn't stop people from buying them at elevated prices anyway.

Orders have been canceled due to CDC stockpiling

Advice can change, but as of now, there's no guidance telling Americans to wear face masks, either the basic surgical face masks or the N95 respirators that health care workers wear to treat infectious diseases.

David Bowman of Phoenix, Arizona, told CNN he'd ordered three respirator masks, which cost him just under $13 each, from Vitality Medical. The medical supply company guaranteed his order would arrive by March 7 at the latest.

But then it was back-ordered until May 29. The notice Vitality Medical sent him said that the CDC had "allocated with our warehouse the item [he] ordered."

The CDC just stole my mask. @CDCgov what gives you the right to steal a mask that I bought and paid for? @VitalityMedical #CoronaVirusUpdates #coronavirus pic.twitter.com/s0rBULyItW — David Bowman (@davbow678) February 27, 2020

"The CDC just stole my mask," Bowman tweeted . "@CDCgov what gives you the right to steal a mask that I bought and paid for?"

Other customers have received similar messages citing requests from the CDC.

"[I] was more alarmed (and frustrated) just trying to get a mask for myself and a few family members," Bowman told CNN in a direct message. "But I thought the government can only seize products like that in an emergency situation, which they seem to be downplaying it [sic]."

CNN reached out to the CDC to confirm it had allocated Vitality Medical's entire supply of N95 respirators and is waiting to hear back. Vitality Medical told CNN that due to restrictions in place with the CDC, all of the N95 respirators on its site were out of stock.

Mask shortages mean fewer available for health workers

Health care workers who treat novel coronavirus patients are at the highest risk in the US for disease transmission, said Dr. Peter Hotez, Baylor College of Medicine professor and dean of the National School of Tropical Medicine.

"That has the potential to be the most destabilizing part of this epidemic," Hotez said. "Even a single death among health care workers ... could make the whole thing unravel."

Preliminary studies suggest as much. In a paper published in the medical journal JAMA earlier this month, 40 health care workers in Wuhan were diagnosed with novel coronavirus after treating patients who had it.

"We have to absolutely make sure that every single hospital in this country has adequate PPE [ personal protective equipment , which includes gloves, masks, face shields, coats and gowns]," he said. "It's not clear that that's the case."

Though federal and CDC officials have said there's no reason to panic, their concern is mounting -- and increasingly public. Earlier this week , US Health and Human Services Secretary Alex Azar said there were 30 million N95 respirators in the National Stockpile. The US needs about 10 times that amount to adequately supply health care workers, he said.

"The overwhelming priority right now is to ensure that all of our hospital frontline staff, clinical staff, have that level of protection," Hotez said. "'Cause if they go down, there's going to be nobody."

Chinese Americans buy masks for families overseas

For the East Asian diaspora in the US, buying masks while they're still available is a necessity for family members abroad. Surgical masks and respirators have been sold out for weeks in the areas where outbreaks are ballooning.

Stefanie Yu, a tech worker in San Francisco, hadn't considered shipping masks to her family in Guanzhong until a friend who'd recently returned from China called her with an urgent message -- buy for your family immediately.

"'Oh, this is happening,'" Yu remembered thinking. "Everyone is trying to get masks."

Every website and major retailer she visited had sold out of every mask. Respirators she clicked open on Amazon were gone within minutes.

She finally found a few from a packaging supply company. She bought 50 boxes with two N95 respirators each, which cost her more than $250.

"Those are disposable," she said. "You're supposed to wear it one time for a couple hours. So it's definitely expensive."

Shipping was even more chaotic, she said. A company that ships to China sent them on February 7 for $80. Then, about a week ago, the company told her it had returned the masks because no planes were flying to China.

The only other option to get the masks to her family would cost her another $80. She paid it.

She's still not sure if the masks made it -- or whether they ever will.

"I'm not the only one who's experienced this," she said. "[The company] was seeing a lot of people shipping masks, and according to them, most of the masks got turned back."

Her family is based in southern China, where the situation is not as severe as it is in Wuhan, where the outbreak originated. Her father still goes on his daily morning run. But every store there is sold out of masks and will be for the foreseeable future.

"I think lots of Chinese people who have overseas resources to buy masks and ship it back will do that," she said.

Empty shelves for N95 masks are the standard now in the US as Americans scramble to buy them up. Some Chinese Americans are sending them to their families overseas where supplies are scarce.

Christina, who lives near San Jose, California, is an "overseas resource" to her nine immediate family members in Hong Kong. She asked to be identified by her first name to maintain her privacy.

She ordered 1,800 face masks for $222 -- "pretty good price" -- from Staples in January. A few days later, her sister in Hong Kong called -- friends in the US had had their orders canceled. A few days later, Christina's order was canceled, too.

The company didn't explain why -- just that they lacked supply, she said.

Christina placed orders with five other companies. All of them were eventually canceled or back-ordered. She eventually gave up on online shopping.

"I visited so many stores," she told CNN. "Walmart, Rite-Aid, Target, even grocery stores and dollar stores. Every place was sold out."

Over two days, she visited 15 stores and found just one box of 20 masks.

So she started getting to stores early. She'd stand outside in line for 30 minutes or more ahead of opening, when she knew stores were restocking their inventory. In January, she was usually the first in line. But now that it's nearly March, the lines are longer and supplies are dwindling.

"Every [store] I go in, the masks are all gone, the sanitizers are gone, alcohol wipes are gone, the gloves are gone," she said. "When you go in the store, you'll know which section it is when you see a big gaping hole with nothing on the shelves."

Xenophobia against Asian Americans persists

Recently, Christina stood in line in front of a local hardware store a half-hour ahead of its opening. She peeked inside and saw masks on display. Then she heard the manager yelling to the employees who were opening up.

"'They're here for masks; don't let them get more than one,'" she said she heard him say. "'Careful, they're going to come back and try to get back in line again.'"

When she got inside, she found a pack of three child-sized masks. She asked the manager if there were any larger sizes.

"He sees I'm holding a pack and said, 'You're already holding one item,'" she said. "He got really peeved."

He asked Christina how many children she has. Two, she said.

He told her three masks should be plenty.

"He said, 'You guys keep coming for these. Leave some for the US people,'" Christina told CNN. "I was like, 'I can't believe what I'm hearing.'"

Disgusted, she left without buying any masks. The manager said they'd be gone by the end of the morning anyway.

"At first, when I started looking for masks, people were really understanding," she said. "But now, when I go up and ask, and I'm Asian, I can feel the look on their face. It's this fed-up look, like 'Oh, they're going to ask for masks again.'"