The authorities are scrambling to contain a rapidly spreading outbreak, restricting travel in 13 cities including Wuhan, the center of the mysterious outbreak. The new virus has sickened more than 800 people in China. Right NowThe new travel restrictions double the number of cities on lockdown. ImageA construction site for a field hospital being built to treat patients with the new coronavirus in Wuhan, China, on Friday.Credit…Chinatopix, via Associated PressChina restricts travel for 35 million people as the death toll rises. The authorities on Friday greatly expanded a travel lockdown in central China to include 12 cities near the center of the outbreak, effectively penning in 35 million residents — nearly the population of Canada — in an effort to contain the deadly virus.The new limits — abruptly decreed ahead of the Lunar New Year holiday, China’s busiest travel season — were an extraordinary step that underlined the ruling Communist Party’s deepening fears about the outbreak of a little understood coronavirus.Just one day after China restricted travel in and from Wuhan, a city of 11 million people and the capital of Hubei Province, and four nearby towns, the government announced plans to suspend public transportation services covering more than half the population of the province. The rapidly expanding outbreak has overwhelmed the province’s hospitals and fueled fears of a global pandemic. Chinese health officials reported on Friday that there had been 26 deaths from and 830 cases of the coronavirus, a sharp increase.On Thursday morning, the authorities imposed a travel lockdown in Wuhan, the epicenter of the outbreak. Airlines canceled hundreds of flights to Wuhan, leaving thousands of people stranded. Later in the day, officials said they would also halt public transportation in the nearby cities of Huanggang, Ezhou, Zhijiang and Chibi, which are together home to more than nine million residents. And by Friday, restrictions had been announced in more cities. China reported two deaths outside the epicenter.The official death toll from the mysterious coronavirus increased by more than a half-dozen in 24 hours, while the number of confirmed cases jumped by more than 200.The majority of the deaths have occurred in Hubei Province in central China, but two deaths have been confirmed outside the epicenter. One patient died in Hebei Province, more than 600 miles north of Wuhan, the authorities announced on Thursday.Another death was confirmed in Heilongjiang, a province near the border with Russia more than 1,500 miles from Wuhan.The disease has also been detected in Vietnam, Singapore, Japan, South Korea, Taiwan, Thailand and the United States, in travelers who had visited China.Residents, some displaying symptoms of the virus, are turned away from overrun hospitals. As Wuhan residents waited in long lines at hospitals to be checked for possible coronavirus infections, some residents complained they were not able to get the treatment they needed.Xiao Shibing, 51, has had a fever for 15 days and has had difficulty breathing. When he went to a hospital, he was not given a test for the new coronavirus, said his daughter, Xiao Hongxia. He was told he had a viral chest infection and was sent home.Mr. Xiao’s family has continued to seek treatment, visiting other hospitals but being turned away by at least three because of a shortage of beds, said his wife, Feng Xiu. “It is like kicking a ball from here to there,” she said.Cai Pei, 41, said his wife began coughing and developed a fever three days ago. He wrote on Weibo that hospitals would not admit her, and he had difficulty finding masks and cold medicine in local pharmacies.They still do not know if she is infected with the new coronavirus or some more common ailment.“Sometimes I can only hide and cry, but I couldn’t tell her and had to reassure her that it is not the virus,” Mr. Cai said by phone. “It is very scary. If it’s real, we have a child and elderly parents at home. What if we all get sick?”Hospitals in Wuhan make urgent appeals for supplies and help.Hospitals and medical workers at the center of the outbreak made urgent appeals for supplies, as stocks of surgical masks and other equipment quickly flew off shelves.“Shortage of medical supplies, request help!!!” the Wuhan Children’s Hospital said Thursday in a post on Weibo, a Chinese social network.The hospital asked for donations of surgical masks, disposable garments, protective goggles and gloves.Several other hospitals, including the Hubei General Hospital, Renmin Hospital of Wuhan University and the Central Hospital of Wuhan posted similar notices.The central government on Thursday acknowledged the severe strain on resources, and the Ministry of Finance announced an urgent allocation of one billion renminbi, about $144 million, for epidemic prevention and control work.State news media also carried reports of people volunteering to help ease the strain on health workers.Young doctors at the Renmin Hospital of Wuhan University volunteered to take on additional shifts or to take over from colleagues with children, the state broadcaster CCTV reported.A team of 30 volunteers in Wuhan mobilized to drive doctors to and from hospitals, while others have offered to help the local Red Cross answer phone calls and publicize requests for help from hospitals, according to a report by the China Business Journal.Masks may help, but experts say it’s more important to wash your hands.Many infectious disease specialists say that cheap, disposable masks that cover the nose and mouth can help prevent the spread of infections if they are worn properly and used consistently.But there isn’t much high-quality scientific evidence on their effectiveness outside health care settings, experts say. Dr. Julie Vaishampayan, chairwoman of the public health committee for the Infectious Diseases Society of America, said surgical masks are “the last line of defense.”The masks will, however, block most large respiratory droplets from other people’s sneezes and coughs from entering your mouth and nose, said Dr. Amesh Adalja, an infectious disease physician at the Johns Hopkins Center for Health Security. Coronaviruses are primarily spread through droplets, he said.Dr. Mark Loeb, an infectious disease specialist at McMaster University in Hamilton, Ontario, said a study during an outbreak of the SARS coronavirus found that any type of protection — whether a mask or a respirator — reduced the risk of infections in health care workers by about 85 percent.“The most important message was that the risk was lower if they consistently used any mask,” he said.But washing hands — frequently and before eating — is universally recommended. Hand sanitizer is effective against respiratory viruses.British and American governments tell citizens to avoid outbreak hot zone. The American and British governments on Friday urged travelers to avoid the city of Wuhan and the surrounding area amid growing signs that the outbreak of the deadly coronavirus is worsening.The American Embassy in Beijing advised travelers from the United States to avoid Hubei Province, where Wuhan is the capital. It said the State Department had already ordered nonemergency government personnel to leave the city. It further warned that the Chinese government might prevent travelers from arriving or leaving.The notice from the State Department was a Level 4 advisory, the sternest warning the United States government issues regarding travel. Other Level 4 warnings issued by the State Department include travel to Syria, North Korea, Afghanistan, Iraq, Venezuela and Yemen, among other places.The warning is a step up from Washington’s earlier cautions. Just a day before, the American government had been advising travelers to “exercise extreme caution” when traveling to the Wuhan area.The British government in a notice dated Thursday similarly advised against all but essential travel to Wuhan.The warnings came as the Chinese government on Thursday began widening travel restrictions to cities surrounding Wuhan. The tougher restrictions apply to cities including Huanggang, Ezhou, Chibi and Zhejiang, affecting millions more people. The Hubei government has imposed some of its own travel restrictions across the province.Reporting was contributed by Chris Buckley, Javier Hernández, Vivian Wang, Austin Ramzy, Elaine Yu, Tiffany May, Russell Goldman, Gillian Wong, Paulina Villegas, Steven Lee Myers, Denise Grady, Karen Zraick, Roni Caryn Rabin, Carl Zimmer and Rick Gladstone. Amber Wang, Albee Zhang, Claire Fu, Elsie Chen, Yiwei Wang and Zoe Mou contributed research.