Patient Portal Flu Vaccine Reminders_RCT 5 (LADHS)

Sub-optimal vaccination rates are a significant problem in the U.S., despite their effectiveness in preventing morbidity and mortality from vaccine-preventable illness. For influenza specifically, annual epidemics of influenza cause substantial morbidity in the U.S. with up to 40,00-80,000 deaths/year and many hospitalizations, emergency and outpatient visits, and significant costs. Reminder/recall (R/R), sent by phone, mail or other modality, can improve child and adult influenza vaccination rates. However, the majority of pediatric or adult primary care practices do not conduct R/R. Barriers are lack of finances, personnel, and algorithms to identify eligible patients. A technological breakthrough that might overcome these barriers involves patient text messaging at the health system level. This randomized controlled trial will assess the effectiveness of reminders messages sent by text encouraging influenza vaccination, on increasing influenza vaccination rates within a health system. Patients will be randomized into three groups: 1) one-third of patients will receive enhanced text reminder messages, 2) one-third will receive enhanced bidirectional text reminder messages and 3) one-third will received standard-of-care text reminder messages. Enhanced texts - Callback by a person: Patient randomized to this study arm will receive a phone call back by a call center agent if they press "1" in response to a question on the original text message. The call center agent's job is to schedule patients for clinical visits. These call center agents will be trained by our faculty and staff and will have the usual HIPAA and other patient confidentiality training. Enhanced Bidirectional Texts: These texts are designed to help schedule a vaccine visit. Patients randomized to this study arm will receive a text message from a call center agent if they press "1" in response to a question on the original text message. The bidirectional texts will have an agent who can answer questions and schedule an appointment through text message back-and-forth conversations with the patient. Bidirectional texts will be exchanged on a HIPAA compliant bidirectional text messaging platform. The patient will use the regular SMS function on their cellphone and the agent will receive and respond to the bidirectional text on the HIPAA compliant platform. Previous studies have shown that low-cost, behavioral nudges through texting can increase influenza vaccination uptake compared to usual care. However, there are limited studies that evaluate the effect of decreasing friction/barriers to scheduling especially within safety net populations. This study will examine the effect of strategies to reduce friction/barriers to scheduling including bidirectional text messages, and texts for patients to call for direct scheduling without wait time on influenza vaccination rates in adults within the 2022-2023 flu season. For the primary analysis, the primary outcome will be the patient's end of flu season vaccination status. Intervention effects will be assessed using multivariable log-binomial regression models. Regressions will include indicators for each intervention as fixed effects, with the standard text condition as the reference group, and potentially clinic random effects, depending on retrospective analysis results. Models will also adjust for patient age, gender, race/ethnicity, insurance, and whether the patient was vaccinated in at least one of the prior two flu seasons. The enhanced texts with callback, enhanced bidirectional texts, and standard-of-care text reminder messages will begin in September of 2022.