When you bring a lunch to work, offer to share some. Or put a dish of vegan cookies next to the coffee pot with a stack of recipe cards. If parents enjoy vegetarian dishes, they're more likely to serve them to their own children. Consider giving gift subscriptions of vegetarian publications to your school's or town's library. Donating vegetarian books helps too.
Most libraries have limited budgets.
Look for the teachable moment. But it might not be a good day to approach the subject if a family member was affected by the outbreak. The middle of Thanksgiving dinner is probably not the best time to discuss turkey production, unless you are specifically asked why you do not eat turkey. Use your best judgement. Some people become vegetarian all at once.