Clinical Research Directory

RANDOMIZED CONTROLLED TRIAL OF TEXT MESSAGE TO INCREASE PNEUMOCOCCAL VACCINATION IN ADULTS IN CHILE.

The goal of this randomized controlled trial is to learn if text message reminders sent through WhatsApp increase pneumococcal vaccination coverage in adults turning 65 years old in Chile. The main questions it aims to answer are: Do text message reminders increase the proportion of adults aged 65 years who receive the pneumococcal vaccine compared to usual care? Do text message reminders increase pneumococcal vaccination coverage within the first 7 days after the message is sent? Is there an association between socioeconomic factors and pneumococcal vaccination coverage in adults aged 65 years in Chile? Researchers will compare adults who receive a text message reminder to adults who receive no reminder (usual care) to see if the reminders increase vaccination uptake. Participants will: Be randomly assigned to receive a WhatsApp text message reminder about the pneumococcal vaccine or to receive no reminder Receive a second reminder on day 14 if they have not yet been vaccinated (intervention group only) Be followed for 6 weeks, with vaccination status checked at days 7, 21, and 42 from the start of the intervention

Reminder Strategies to Improve Meal-Logging Adherence

This study is a single-center micro-randomized trial, aiming to examine the effects of two theory-driven reminder strategies on adherence to repeated, image-based meal logging in adults age 45 and older. Three times daily, participants are automatically randomized to receive one of three reminder messages prior to each habitual mealtime. The main research questions the trial aims to answer are: * Do loss-framed reminders (emphasizing loss of a daily financial reward for not logging) increase meal logging adherence in the two hours following a reminder, compared to a neutral reminder? * Do logging consistency reminders (providing feedback on recent logging streaks) increase meal logging adherence in the two hours following a reminder, compared to a neutral reminder? * Do the effects of loss-framed and logging consistency reminders differ from each other? Primary aim: To estimate the proximal effect of each reminder type on whether a participant logs a meal within two hours of receiving a reminder. Secondary aim: To examine whether within-person physiological patterns (e.g., heart rate variation) moderate response to reminders, with the goal of identifying physiological markers of receptivity to behavioral prompts. The trial aims to enroll 200 adults aged 45 and older. Participants attend a baseline visit for onboarding, consent, and device setup, followed by a 28 day remote intervention period during which they should photograph their meals three times daily (breakfast, lunch, dinner) and wear a smartwatch and smart ring continuously. Prior to each mealtime, they receive an automatically randomized reminder message. Participants earn a daily financial reward contingent on completing meal logging for that day. Note: This trial was registered retrospectively as enrollment began prior to registration. However, registration was completed before data collection was finished and before any data analysis was conducted.