It's not uncommon during unprecedented eras of emergency to see something that would usually take a long time go much quicker instead in terms of technology. See the development of armoured warfare during the two world wars, flight and so on. When Mustard Gas, Lewisite etc. became an issue, counter measures were found rapidly.
When this got serious, there was no doubt in my mind a vaccine would be made quicker than usual, simply because of the urgency and collaboration. It doesn't mean the quality of it will be lax - indeed, quite the opposite; the focus on it will be so extreme as to make the manufacturers desperate to get it right.
I have no doubts really that the vaccine will be safe. Very few aren't. The worst case scenario really is that it doesn't work.