In English-speaking countries, the common verbal response to another person's sneeze is "bless you", or, less commonly in the United States and Canada, "Gesundheit", the German word for health (and the response to sneezing in German-speaking countries). There are several proposed bless-you origins for use in the context of sneezing.

Answer this question based on the passage: what to say when someone sneezes instead of bless you? Let's have some stream of consciousness first.
The relevant information is: In English-speaking countries, the common verbal response to another person's sneeze is "bless you", or, less commonly in the United States and Canada, "Gesundheit", the German word for health (and the response to sneezing in German-speaking countries). So, the answer is Gesundheit.