article_snippet.sent: Sending a spit sample is voluntary, and users only become eligible once users've completed 15 of the Health History Survey questions, and each of the Health Tracking Surveys over two separate days.
article_snippet.sent: Sending a spit sample is voluntary, and users only become eligible once users've completed 15 of the Health History Survey questions, and each of the Health Tracking Surveys over two separate days.
article_snippet.sent: Sending a spit sample (illustrated) is voluntary.
highlights_snippet.sent: Participants can also send a spit sample that is tied to the results of the surveys .
  