The entire 11 million population of Wuhan will undergo testing after the coronavirus made an unwelcome return to the city where it was first detected in late 2019. According to the Associated Press, three cases were confirmed in the Chinese city on Monday—the first non-imported cases there in over a year—and authorities have rushed to stamp out the new outbreak. All 11 million people who live there will be tested this week. Nationwide, China is seeing one of its most severe outbreaks in months, with more than 300 cases recorded over the past 10 days. BBC News reported that 15 provinces have been hit by local infections, including the capital city of Beijing. Chinese authorities have confirmed that the highly infectious Delta variant appears to be driving the spike in case numbers.