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A China-made aerosolized adenovirus vector COVID-19 vaccine has proved safe in phase-1 clinical trials. The adenovirus type-5 vector-based COVID-19 vaccine (Ad5-nCoV) was jointly developed by the Academy of Military Medical Sciences, Zhongnan Hospital of Wuhan University, and other Chinese institutions. Previous work in animal models has shown that a single Ad5-nCoV protects from wild-type SARS-CoV-2 replication in the upper respiratory tract. Mucosal immunity has potential benefits in triggering mucosal and systemic immune defense, thereby preventing pathogens from invading the mucosal surface. According to the paper published online in Lancet Infectious Diseases, last September, 130 volunteers were enrolled and randomly assigned into five groups to be vaccinated via intramuscular injection, aerosol inhalation, or both. The participants in the two aerosol groups received an initial high dose or low dose of Ad5-nCoV vaccine on the first day, followed by a booster on day 28. The mixed vaccination group received an intramuscular vaccine on the first day, followed by an aerosolized booster shot on the 28th day. The intramuscular groups received one dose or two doses of Ad5-nCoV on the first day. According to the paper, the inhaled vaccine is well tolerated. One dose of aerosolized Ad5-nCoV, equal to one fifth of an intramuscular dose, induced a strong response. After the first injection in the arm, an inhaled booster vaccination on the 28th day induced robust antibody responses. Hou Lihua, a researcher at the Academy of Military Medical Sciences, said the vaccine does not need to be injected, and the adverse reactions such as arm pain and swelling will not occur, which can improve people's willingness to be vaccinated. Meanwhile, the dose of the inhaled vaccine is very low, which is equivalent to greatly increasing vaccine production and also solves the issue of medical waste such as syringes. The vaccine is currently undergoing phase-2 clinical trials.
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