You are now immune to all diseases. Unfortunately, your immunity comes at the cost of the immune system of every other being on the planet. Men, women, children, dogs, cats, beasts of burden, and everything else that lives begin to die from viruses that normally would be fought off in a matter of hours. Plants lose their symbotic relationship with helper fungi and bacteria that are also destroyed in this global pandemic. Eventually it's just you. Now, that's great and all, but the planet's infrastructure is not really set up for infinite run time in automatic. After a time, the necessities of life start to go away. First, the electricity. Then, the water (as the backup generators supplying the pumps run out of fuel). With no plants to eat, no animals to hunt, and no refrigeration to preserve the remaining food supply, you quickly reach the point of starvation. It's either that or a bullet to the brain--take your pick.
I wish for denial.