Influenza remains a potentially significant and largely preventable source of morbidity and mortality, yet vaccine coverage is low. Young children are at particular risk for underimmunization because they may need to receive 2 doses in a current season. Even among those young children that initiate vaccination, only 40% receive the important second dose, yet one dose does not confer adequate protection. Low-income, urban children may be at particular risk of not receiving two doses. While traditional mail and phone immunization reminders notifying families that a vaccine is due have had limited efficacy in low-income, urban populations, we have demonstrated the success of using text messages. Comparing the effectiveness of different forms of reminders on receipt of this critical second dose of influenza vaccine has not been studied. Besides failure to remember to return for subsequent doses, receipt of 2 doses of influenza vaccine in a season can be affected by limited health literacy regarding influenza vaccination, particularly associated with understanding the need for a second dose since not all children require it. Text messaging offers the ability to combine health literacy promoting information and reminders in a scalable, efficient manner for populations at high risk for underimmunization, limited health literacy, and influenza spread. Therefore, the purpose of this study is to determine whether the provision of interactive vaccine health literacy-promoting information in text message vaccine reminders improves receipt and timeliness of the second dose of influenza vaccine within a season for underserved children in need of two doses.

Inclusion Criteria:

• Parenting adult of child age 6 months through 8 years
• Child receives care at study site (visit in last 12 mths)
• child received influenza vaccine and needs a second this season
• Parent has cell phone has text message capability
• Parent speak English or Spanish
• Can read text messages

Exclusion Criteria:

• Parent does not speak English or Spanish
• Parent does not have cell phone with text messages