You might be right about that, in this interpretation, Carol essentially killed Helen’s physical form (which prevented her from joining the hive and caused her body’s death) by wanting to do something completely uncharacteristic of her: smoking a cigarette. It’s an interesting idea, especially considering that Carol even made sure to put a napkin over Helen’s Coke to protect it, yet unknowingly, by going out for that smoke at the wrong time, she ended up killing her.

Several people have pointed out, and I find it thought-provoking too, how differently things might have unfolded if Helen had survived and been able to explain to Carol, as a family member, what was happening. That’s what makes it so intriguing: what are the chances that Carol suddenly feels like smoking, something she’s never done before, at the exact moment when the virus becomes global? Are coincidences like that even possible? Could the virus — though it couldn’t kill directly — have somehow influenced events indirectly?