Regarding “how do you verify that it works?”, specifically regarding the concerns whether the generated antibodies will bind to the virus and antibody enhanced disease concerns. , Right now there is a $600 test selling online (at a reputable source) that can verify whether the antibodies are neutralizing (=block the virus replication). It tests whether the generated antibodies bind to the RBD (Receptor Binding Domain) of the virus and block it from binding to the ACE2 receptor of the human cell (this is how the virus gets into the cell). It does so in a extremely simple way: it contains RBD and an ACE2 proteins plus some stuff to detect when they bind. There exist other ways to do so, but they are more expensive and not widely available. This is how advanced the science actually is, we can commercially create somewhat arbitrary parts of human cells and viral particles for a $600 price and <1 year of development.
So you can test whether the vaccine should work via antibodies IF it elicits a sufficient immunity response measured by high antibody titer. There are already widely available antibody tests to measure the antibody titer. So if you have a candidate vaccine, you order corresponding antibodies for it (also available online), test that they block the ACE2 binding, give it to humans once you are sure that it is kind of safe (peptide vaccines are) and measure the antibody titer. If it is high enough, it is very likely that the vaccine works.
You don’t need challenge trials. You still need to check for safety, but after this is done, you can simply distribute it to people, measure their antibody response and monitor whether they get sick. If they do at a substantial rate and there are no explanatory circumstances (e.g. weak immune system, very high viral load), well, something went wrong… Otherwise, all good!
Regarding “how do you verify that it works?”, specifically regarding the concerns whether the generated antibodies will bind to the virus and antibody enhanced disease concerns. , Right now there is a $600 test selling online (at a reputable source) that can verify whether the antibodies are neutralizing (=block the virus replication). It tests whether the generated antibodies bind to the RBD (Receptor Binding Domain) of the virus and block it from binding to the ACE2 receptor of the human cell (this is how the virus gets into the cell). It does so in a extremely simple way: it contains RBD and an ACE2 proteins plus some stuff to detect when they bind. There exist other ways to do so, but they are more expensive and not widely available. This is how advanced the science actually is, we can commercially create somewhat arbitrary parts of human cells and viral particles for a $600 price and <1 year of development.
So you can test whether the vaccine should work via antibodies IF it elicits a sufficient immunity response measured by high antibody titer. There are already widely available antibody tests to measure the antibody titer. So if you have a candidate vaccine, you order corresponding antibodies for it (also available online), test that they block the ACE2 binding, give it to humans once you are sure that it is kind of safe (peptide vaccines are) and measure the antibody titer. If it is high enough, it is very likely that the vaccine works.
You don’t need challenge trials. You still need to check for safety, but after this is done, you can simply distribute it to people, measure their antibody response and monitor whether they get sick. If they do at a substantial rate and there are no explanatory circumstances (e.g. weak immune system, very high viral load), well, something went wrong… Otherwise, all good!