some ideas for my story

I'm planning on making the whole vampire thing less myhical and more scientific. So, Laura, I'll need your help to make that seem more real. It's going to be like this...in like the early 1000's some crazy genius medicine guy was trying to make a medicine that made us all healthier, it would cure any hing and make us better. What it did was create super humans(aka vampires) stronger faster, better sight hearing everything
but a side effect, super humans have super sensitivity. for one, we get sun burn when we are in the sun too long, so do these vampires but it happens way faster and it gets a lot worse. to the point where their skin boils within a minuteof being outside
Garlic...is a very base substance that can easily irritate the skin, so it burns them a little. (myth solved) holy water- way back when they were first made the people accused the medicine man of the devil's work because they did not inderstand this super human stuff, the religious people would make holy water with blackseed oil(an oil known to irritate the skin) and they would throw it on the vampires
when they would burn it was said that they were evil, for their bodies were rejectin the holy water (myth solved). So basically every ting is going to be explained
something abut immune systems being so great is preserves the body::immortality timeless youth
because they are super thay need a stonger life force/form of food
blood is what they discovered worked best
therefore the ones with this(disease I'll call i for now) evolve to have fangs in order to make their food more accesible. (myth solved)
now, I don't have all of the details for these theories but if something doesn't sound right please bring it to my attention
but here it is, the base of my story
I have the base some characters and even a first chapter but no plot...I have very little idea of what I'll do with this story