The development of the vaccine was cancelled on 11 December 2020 during its
Phase I trial, after a number of trial participants were found to give
false positive test results for
HIV antibodies when they did not in fact have HIV. This was due to the HIV virus fragment used as a molecular clamp leading to "a partial antibody response" to HIV. This is an undesirable outcome as it will interfere with future
HIV screening tests for affected participants. Nine days prior to the termination, on 2 December, the first
emergency use authorisation had been granted to a COVID-19 vaccine; the
Pfizer–BioNTech COVID-19 vaccine in the United Kingdom. Following the termination of V451, vaccine production capacity by CSL Limited was diverted to the
Oxford–AstraZeneca COVID-19 vaccine. == References ==