-Kate passes out at the press conference and is placed in quarantine and given 72 hours to live.
-Needles found by the police prove that patient zero took the drug interferon to prolong his life to infect more people.
-Peter tracks Dani's last days and realizes she and several others contracted the disease on a city bus. Through surveillance video they find Jacob, their patient zero spreading the disease on the bus hand rails.
-Through bed bug bites on two victims, they track Jacob to a motel and find him outside at a subway station where Peter shoots him.
-The CDC has an experimental vaccine for the virus. Charlie tries it on a patient who dies and is later fired for it.
-Megan realizes that the patient who died had an underlying medical condition that caused his death, not the vaccine. They try the vaccine on Kate and she lives.