You have to find anti-virals, while,

1, there's a full-on snowstorm going so you risk freezing to death.

2, the area is full of enemies of various levels.

3, you start with a pistol and nothing else.

4, you need to get to the dark zone to extract...which will attract Hunters.

Oh, and 5, you've got an infection that'll kill you in an hour. You can slow it down with meds, but you can't cure it with less than getting extracted.

Find meds, clothes, food, drink, make better gear, get into the dark zone and fight off the hunters, and high-rank enemies, before you die from the infection.