HONG KONG, Sept. 10 (Xinhua) - The University of Hong Kong (HKU) said on Wednesday that the clinical trials of a nasal spray vaccine for COVID-19 jointly developed by the university's Department of Microbiology and mainland institutions have been approved. The State Key Laboratory of Emerging Infectious Diseases has been working on the vaccine with Xiamen University and Beijing Wantai Biological Pharmacy. It is the first nasal spray COVID-19 vaccine approved by China's National Medical Products Administration for clinical trial in humans. The HKU said in a statement that its vaccine strategy has been selected as one of the five vaccine technologies by the Ministry of Science and Technology for further evaluation.