Another candidate COVID-19 vaccine for Phase I clinical trial is from the University of Oxford and AstraZeneca (NCT04324606).68 Around 1110 people will take part in the trial, which started recruitment at the end of April 2020. The vaccine is based on a chimpanzee adenovirus vaccine vector (ChAdOx1) and the SARS-CoV-2 spike protein. Chimpanzee adenoviral vectors against different pathogens have been already tested in thousands of subjects with demonstrated safety. To date, ChAdOx1 has been administered to six rhesus macaques exposed to high doses of SARS-CoV-2. The vaccine was unable to prevent infections, although it reduced the severity of the disease: no signs of virus replication were observed in the lungs, with significantly lower levels of respiratory disease and no lung damage compared to control animals, according to a recent article deposited in bioRxiv.69 Another adenoviral vector vaccine developed by CanSino Biological Inc. and Beijing Institute of Biotechnology using a genetically engineered replication-defective adenovirus type 5 vector to express the SARS-CoV-2 spike protein (Ad5-nCoV) is currently being tested in Phase I/II trials (NCT04398147, NCT04341389, NCT0431312).