I understand the worry about people thinking vaccines will work like magic (vaccine approved on Monday, everyone gets it by Wednesday, pandemic over by the weekend!)
At this point though I’m not sure there is that much unfounded optimism around, and I’m more concerned about the effects of squashing down hope. We need hope - not only for our own mental health, but to get people to stick with the restrictions currently in place until we can replace them with a vaccine.
People are currently sticking with restrictions in the awareness that these are temporary, that they won’t be over immediately but that they will be over in the not-too-distant figure, and vaccines are one of the things that will get us there. Too many dire warnings about how vaccines “won’t be a magic bullet”, might not work that well, might not stop infection, might not stop the spread of the pandemic, won’t replace masks and social distancing, and on and on, risks getting people to believe that there’s no point even taking a vaccine (after all, if it won’t even work that well and it won’t replace masks and distancing, why bother?), which is really not going to help. Also, and possibly worse, it’ll lead people to start thinking “well if even the vaccines aren’t going to get us out of this, I am not going along with all these restrictions any more, I’m going to go and hug my mum.”
Yes vaccines probably won’t be perfect, might need yearly injections, might just reduce symptoms and infectivity rather than totally eliminate them. But even that would be brilliant. We could turn Covid into flu, or a cold! We could drastically reduce the rate of people getting infected! That would go a long long way to getting us back to our normal lives.
We don’t need a perfect vaccine, right now, we just need a vaccine that will have some effect (which any of them will or they wouldn’t be licensed). We should not let the perfect be the enemy of the good here, and we shouldn’t kid on to ourselves that nothing will really improve much until perfect arrives.