You pick up the syringe and inject it into your arm. You feel a.prickling as your body hair recedes, and a pair of D-cup breasts balloon out of your chest. Your ass swells and grows, and you facial features soften and become more feminine. A tingling feeling at your crotch alerts you to you dick and balls shrinking, before dissapearing. A pussy grows there in place of your manhood. Your dark hair turns a red and lengthes to your soft ass.
You are now a woman! And a damn sexy one too, with an hourglass figure and big breasts. However, your mind is no different from before you plunged a mysterious syringe full of an unknown liquid into your arm. You feel stronger, and something tells you this may have been the cure.
You need to find some science person. You can save the world!