World War Z — Ending Explained

Gerry's investigation points to a weakness in the virus, which the dialogue describes as hiding behind its apparent strengths. The virus avoids hosts who are already seriously ill. Gerry deliberately infects himself with a deadly pathogen to test the idea, and the infected ignore him. This gives humanity a form of camouflage.

Gerry's family is reunited at the end. The closing narration says the war is not over and calls on people to fight. The ending is hopeful but open.

Details of the individual set pieces are not covered in my search results, so they are left out here.

The film can be read as an allegory for a global pandemic and for how governments handle a crisis they do not believe in until it is too late. It can also be read as a story about border walls and isolation, which fail against a threat that goes around them. A third reading sees it as a family drama, in which the apocalypse is a backdrop to Gerry's choice between protecting his family and serving everyone else.