First, I expect a disproportionate number of vaccine trials are for “unusually difficult” viruses, like HIV. After all, if it’s an “easy” virus to make a vaccine for, then the first or second trial should work. It’s only the “hard” viruses which require a large number of trials.
But if it’s easy to develop vaccines, why has there been no coronavirus vaccine previously? Why is there still no vaccine for SARS 1 or MERS or the common cold? Why was this Radvac idea or something similar not rolled out pre-Covid?
I expect this is still mainly a result of regulatory hurdles. Clinical trials are slow and expensive, so there has to be a pretty big pot of gold at the end of the rainbow to make it happen. Also, companies tend to do what they already know how to do, so newer methods like mRNA or peptide vaccines usually require a big shock (like COVID) in order to see rapid adoption.
Good questions.
First, I expect a disproportionate number of vaccine trials are for “unusually difficult” viruses, like HIV. After all, if it’s an “easy” virus to make a vaccine for, then the first or second trial should work. It’s only the “hard” viruses which require a large number of trials.
I expect this is still mainly a result of regulatory hurdles. Clinical trials are slow and expensive, so there has to be a pretty big pot of gold at the end of the rainbow to make it happen. Also, companies tend to do what they already know how to do, so newer methods like mRNA or peptide vaccines usually require a big shock (like COVID) in order to see rapid adoption.