What are the factors in assessing a vaccine? Offhand I would say effectiveness, safety, persistence, and cost. So, for example, the smallpox vaccine produced protection against smallpox for 95% of those who received it (highly effective), the protection lasted for decades (persistent), .1% of those vaccinated experienced serious reactions and .001% experienced life-threatening complications (generally safe), and it cost about %5 per patient (inexpensive) so it was a good vaccine.
Assuming that 30% of the population is susceptible to SARS-CoV-2 (that’s roughly how many people contracted “Spanish flu” in the U. S. in 1918) and that the case mortality rate is 4% that means that for a COVID-19 vaccine to be safe enough, it would be reasonable say that the prevalence of severe complications should be no more than 1.2% of those immunized (preferably much less). How long should it last? I would think that immunization with a short half-life would be no better than no immunization at all.
As to cost a vaccine could be pretty expensive and still be worthwhile. No wonder so many companies are trying to find one. I’m actually more worried about effectiveness, safety, and persistence. Those are why I’m skeptical of a good vaccine being developed in the next year.
Cynical me says that since no vaccine for COVID-19 will ever be considered ‘safe’ enough (meaning utterly no possibility of death or illness from taking it) much less effective enough to be made available for general distribution, lockdowns and total mask-wearing will have to remain in effect until at least after election day in November in case of a resurgence or in case any other wildly dangerous epidemic (like from the Rhinovirus family) shows up ‘unexpectedly’.
These people have to know no COVID vaccine has ever been made for humans. If they don’t, they’re too ignorant to be allowed to work on a vaccine, because it is obvious to me that they’re not chasing a cure or a preventative, they’re chasing taxpayer dollars. When you subsidize something, you get more of it.
You might want to peruse this,
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7284272/
This is a summary of the effectiveness of coronavirus vaccines for domestic animals. It is a mixed bag with few real successes.
One might remember that the common cold is the result of several different coronaviruses, and there is no vaccine for any of them.
RNA viruses like COVID-19 are notorious for rapid mutation, which makes vaccines have a limited utility.
If I were a betting person (not since the first Liston/Clay fight, lost a week’s lunch money), I would bet against the development of a disease.
Another reason not to repeat the lockdowns.
I’m not sure “persistence” needs to be any longer than a flu vaccine.
There really does seem to me to be some evidence of immunological effects either acquired by genetic happenstance or from previous encounters with corona viruses or from cross-protections from other vaccines. This suggests to me that a vaccine will be successful at least in modest terms at first.
That several countries seem to be making progress is a good sign, though I think the worldwide fear is that the bottle-neck will be material capacity and China/USA will divert most of it to themselves. I’m not as concerned about people telling pollsters they won’t vaccinate; most of them won’t be given the opportunity at the outset.
I should add: I wouldn’t assume a vaccine at any given time and efficacy for public health policy purposes.
It needs to be six months or longer for the very reason that COVID-19 is more virulent than seasonal flu.