While every state in the U.S. has now announced the end of mask mandates to mitigate the spread of Covid-19, officials in China and other countries are ramping up restrictions amid new surges in infections.\r\n\r\nA number of large cities in China have been placed in partial or full lockdown as public health officials in the country reported Sunday that Covid-19 cases doubled from the previous day, with 3,400 confirmed daily cases.\r\n\r\n\u0022Once we let our guard down, it\u0026#039;s possible that [infections] will bounce back and rise again.\u0022\r\n\r\nShenzhen, a city of 17.5 million people, entered lockdown on Monday. Residents are barred from leaving the city except in special circumstances and must test negative for the coronavirus 24 hours before leaving. All residents are also undergoing three rounds of testing and businesses have been ordered to close or shift to remote work.\r\n\r\nThe restrictions are set to stay in place until at least March 20 as more than a dozen Chinese provinces fight outbreaks of both the Delta and Omicron variants, according to The Guardian. The latest surge is reportedly being fueled by Omicron.\r\n\r\nChina has relied on a \u0022zero-Covid\u0022 approach since the coronavirus was first detected in Wuhan in late 2019, imposing strict mitigation measures when outbreaks occur, and has managed to keep its death rate low compared to much of the rest of the world.\r\n\r\nSunday marked the fourth consecutive day the country reported more than 1,000 daily cases, with 19 of China\u0026#039;s 31 provinces affected so far.\r\n\r\nIn Hong Kong, officials reported more than 32,400 cases on Sunday—the city\u0026#039;s worst outbreak since the pandemic began. Hospitals have become overrun, with patients being treated in lobbies and mortuaries filling up so quickly that \u0022body bags were being crammed into wards with patients who were still being treated for the virus,\u0022 according to the New York Times.\r\n\r\nThe reports recall the severe outbreaks that several U.S. cities have faced over the course of the pandemic, but bear little resemblance to the current policies being implemented in the United States as mask mandates are lifted and the country\u0026#039;s top public health official, Centers for Disease Control and Prevention (CDC) Director Rochelle Walensky, says future surges will only be \u0022annoying\u0022 for many.\r\n\r\n\u0022People should not get the wrong impression that the virus situation is now under control,\u0022 Dr. Albert Au of Hong Kong\u0026#039;s Center for Health Protection told The Guardian. \u0022Once we let our guard down, it\u0026#039;s possible that [infections] will bounce back and rise again.\u0022\r\n\r\nShanghai, China\u0026#039;s most populous city, is also under new restrictions as the outbreak accelerates. The city\u0026#039;s schools have shifted to remote learning and its bus services were halted over the weekend.\r\n\r\nThe northeastern province of Jilin was reported to be the hardest-hit area in China on Saturday. Hundreds of residential neighborhoods in Jilin City were locked down over the weekend, as several hundred Covid-19 cases were detected there and in Changchun.\r\n\r\nAccording to the Times, nearly half of the new cases announced Sunday in China, where more than 85% of the population has been fully vaccinated, did not cause initial symptoms.\r\n\r\nOn Twitter, epidemiologist Eric Feigl-Ding also pointed to a rise in cases of the Omicron subvariant, B.A. 2—commonly called the stealth\u0022 Omicron variant—in South Korea:\r\n\r\n\r\n\r\nIn the United Kingdom, health secretary Sajid Javid warned Monday that the country is likely to see a surge in cases, just over two weeks after Prime Minister Boris Johnson lifted all public health restrictions.\r\n\r\nThe country reported nearly 73,000 cases of Covid-19 on Friday, up from about 39,000 on February 24, when most restrictions ended. In the week ending March 5, one in every 25 people in England were estimated to have Covid-19, as well as one in every 13 people in Northern Ireland and one in every 18 people in Scotland.\r\n\r\nIn the U.S., public health experts urged Americans to remain alert about a potential new surge in cases.\r\n\r\n\r\n\r\n\u0022Haven\u0026#039;t we learned that as cases rise anywhere they\u0026#039;ll likely rise here too?\u0022 asked Dr. Beth S. Linas, an epidemiologist at Johns Hopkins University.