China virus

In late December Chinese health officials were aware of a new Sars like virus. 27 cases are uncovered but they identify no human to human contact. Chinese health officials are reprimanded for " spreading rumors". In early January news leaks to the Chinese press and the government officially says there is no human to human contact. On January 7 the Chinese government says they knew about the virus from an early date. On January 13 the first case outside of China hits a man in Thailand who had just returned from Wuhan. On January 15 the first US case is confirmed on a man who had just returned from Wuhan. January 23 Wuhan is put on lock down but travelers are still allowed to leave Wuhan and go to other countries around the world. On January 30 the WHO declares a public health emergency after 82 confirmed cases outside of China. China stopped air travel between provinces on January 20th but waited until the end of March to stop travel overseas. The various conspiracies about China's deliberate attempt to cause problems are based on the question, if they thought it was serious enough to stop travel within China in late January, why did they wait until late March to stop travel outside of China.