Even after we’ve found the perfect component to use for the vaccine, we need to run tests, both in animal models and in human clinical trials. In animal models, we need to make sure that the vaccinated animals are really immune to the disease. After the mice receive the polio vaccine, for example, we try to give them [real] polio, to confirm they’re immune. In human trials, we need to make sure that humans respond similarly to the animal model.
Dr. Westreich, would you please explain Antibody-Dependent Enhancement ADE). I’ve been worried that the presence of ADE in animal tests for a SARS vaccine led to the abandonment of a vaccine for SARS. Covid-19 is related to SARS so this is of concern. Please share any insights you have in this regard. If ADE means a Covid-19 vaccine will only help people avoid re-infection and actually
people who have not ever been infected (like the Dengue vaccine), then Covid-19 could turn out to be a very difficult to control and disruptive force indeed.
UPDATE: This excellent discussion sheds some light on these issues: