Beijing, July 22 : Nanjing, capital of China's Jiangsu province, launched an all-inclusive nucleic acid testing campaign after 17 airport workers tested positive for Covid-19. Medical personnel continued the testing campaign overnight in residential communities, reports Xinhua news agency. Community workers and volunteers have been mobilised to help maintain order as people queue for tests. The mega-city with a population of more than 9.3 million has classified 10 areas as medium-risk for Covid-19 and implemented closed management. The 17 airport workers were tested positive for Covid-19 during a routine nucleic acid testing for airport staff. The municipal government has urged residents not to leave the city unless necessary. Anyone leaving the city must produce a negative nucleic acid test certificate issued within 48 hours of their departure. The rule does not apply to transit passengers. /IANS