The University of Oxford is leading the way in developing a SARS-CoV-2 vaccine. They tested their vax on six rhesus monkeys and all remained virus free after 28 days of sustained exposure to the virus. The monkey experiment was carried out in late March by US vscientists at the Rocky Mountain Laboratory in Hamilton, Montana as reported by the New York Times Monday 4/28.
In this pre-clinical trial, Six rhesus macaques received a vaccine produced by the Jenner Institute and the Oxford Vaccine Group. They were then exposed to heavy levels of the coronavirus that previously sickened other monkeys. The vaccinated monkeys suffered no ill effects and remained healthy at least 28 days later. Safety trials for the vax have begun in humans as a prelude to efficacy trials in a large number of people.
These are encouraging, but very preliminary results. One concern when trying to develop a vax to a new virus is that the immune response generated by the vax might actually be detrimental to the patient. For example, the infectiveness of Dengue virus can actually increase due to an immune response to the virus. A consortium of EU and US health agencies recently formed and met virtually to oversee the numerous vax trials underway or soon to be launched, and they pointed out that a deleterious immune response to CoV-2 was one of the first things they needed to understand.
However, if this Oxford study holds up, it could go a long way to minimizing the fear that an immune response could actually exacerbate COVID-19. That would represent a significant hurdle surmounted.