Patient Portal Flu Vaccine Reminders (5) | NCT05525494

ID	Type	Description	Link
R01AI135029	U.S. NIH Grant/Contract		View source

Name	Class
National Institute of Allergy and Infectious Diseases (NIAID)	NIH

Description Module

Brief Summary

This trial is taking place in Los Angeles, CA at clinics within the UCLA Health System.

The study design is a 2x2 nested factorial design. Patients will be randomized into 1) receiving text based reminder messages with direct scheduling link, 2) portal-based reminder messages with direct scheduling link, or 3) the control group. Patients randomized to the intervention arms will receive reminders if they are due for influenza vaccine.

Nested within the portal reminder arm, we will have two additional components for which patients will be randomized separately:

A pre-commitment prompt, asking patients which time (September, October, November or December) and which place (UCLA, pharmacy, workplace or school, or other) they plan to get their Influenza vaccine with tailored monthly messages based on responses (pre-commitment message with tailored recall messages with direct scheduling vs. standard portal reminders with direct scheduling).
A pre-appointment reminder encouraging patients to ask for their influenza vaccine at their upcoming appointment (pre-appointment reminder encouraging influenza vaccination vs. standard pre-appointment reminder not mentioning influenza vaccination)

Nested within the text message reminder arm, we will have one additional component for which patients will be randomized separately:

1) A pre-appointment reminder encouraging patients to ask for their influenza vaccine at their upcoming appointment (pre-appointment reminder encouraging influenza vaccination vs. standard pre-appointment reminder not mentioning influenza vaccination)

Despite the Advisory Committee on Immunization Practices (ACIP) recommendation in 2010 that all people above 6 months of age should receive an annual flu vaccine, vaccination rates remain low: at 6m-4.9 yrs. (70%), 5-17.9 yrs. (56%), 18-64.9 yrs. (38%), and >65 yrs. (63%). The investigators will assess the effectiveness of MyChart R/R messages and text R/R messages as compared to the standard of care control (no messages).

Detailed Description

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 portals-- secure, web-based communication systems, embedded within electronic health records (EHRs), for patients and providers to communicate with each other via email and the internet. Portals are used by about half of Americans and half of UCLA patients. Another is text messaging at the health system level.

This randomized controlled trial will assess the effectiveness of reminders messages sent to portal users, 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 reminder messages with direct scheduling and pre-appointment reminders via the portal, 2) one-third will receive reminders via text messages with direct scheduling and pre-appointment reminders sent by the health system and 3) one-third will not receive reminders.

Patients in the portal-based reminder arm will be further randomized (separately) for two additional components: pre-commitment messages with tailored recall messages and pre-appointment reminders. Patients in the text message-based reminder arm will be further randomized for an additional component: pre-appointment reminders.

Direct scheduling: The convenience of scheduling an appointment for influenza vaccination may increase the likelihood that patients receive an influenza vaccination. All patients receiving reminders (intervention groups) will receive flu vaccine reminder letters with a link to the MyChart direct appointment scheduling page.

Pre-appointment flu reminders: Finally, a missed opportunities for vaccination occurs when patients are eligible for vaccination but are not offered a vaccine at their medical appointment. Pre-appointment reminders, sent in advance of an upcoming appointment, encouraging the patient talk to their doctor about influenza vaccination, may increase the likelihood of that patient receiving a vaccine. Patients in both the portal-based and text message-based reminder arms will be randomized to one of two groups: 1) one half will receive modified pre-appointment reminders that mention influenza vaccination and 2) one half will receive the standard pre-appointment reminders for an upcoming appointment (no mention of influenza vaccination).

Pre-commitment prompts with tailored monthly reminders: pre-planning the place and time of the flu vaccination may improve follow-through. A pre-commitment prompt will be sent via the portal in early September asking patients to commit to a time (September, October, November or December) and place (UCLA, pharmacy, workplace or school, or other) for their flu vaccination. Tailored monthly messages will be sent to patients based on their response to the pre-commitment prompt sent in September. Patients in the portal-based reminder arm will be randomized to one of two groups: 1) one half will receive the pre-commitment prompt and tailored monthly reminders, 2) one half will receive standard monthly reminders.

Interventions that apply Behavioral Economics principles in vaccine promotion messaging can increase vaccine receipt. We will include ownership language in the pre-appointment messages. The convenience of reminders sent via text and with a Direct Appointment Schedule link included enables patients to self-schedule a flu vaccine only visit, reducing friction for vaccine receipt. Additionally, the pre-commitment prompt with tailored reminders will test the principle of implementation intention (pre-planning the place and time of the flu vaccination) has been shown in other health behavior studies to improve follow-through.

For the primary analysis, the primary outcome will be the patient's end of flu season vaccination status. Intervention effects will be assessed using mixed effects log-binomial models. Models will contain terms for messaging modality (text v. portal v. none), pre-appointment reminders (sent v. not sent), and pre-commitment prompt (sent v. not sent).

The portal-based pre-commitment prompt will be sent in September of 2022. The R/R text and portal reminder messages and pre-appointment reminders and will begin in October of 2022.

Arms/Interventions Module

Arm Groups

Label	Type	Description	Intervention Names
Text Fixed R/R Messages with Direct Appointment Schedule Link + Text Pre-Appointment Reminders	Active Comparator	Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder via text when they schedule a visit during the study period.	Behavioral: Text Fixed R/R Messages with Direct Appointment Schedule Link Behavioral: Text Pre-Appointment Reminder
Text Fixed R/R Messages with Direct Appointment Schedule Link	Active Comparator	Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment.	Behavioral: Text Fixed R/R Messages with Direct Appointment Schedule Link
Portal Pre-Commitment Prompt, Tailored R/R Messages w/ Direct Scheduling + Pre-Appointment Reminders	Active Comparator	Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly by portal based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period.	Behavioral: Portal Pre-Commitment Prompt with Tailored R/R Messages with Direct Appointment Schedule Link Behavioral: Portal Pre-Appointment Reminder

Interventions

Name	Type	Description	Arm Group Labels	Other Names
Text Fixed R/R Messages with Direct Appointment Schedule Link	Behavioral	Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment.

Measure	Description	Time Frame
Number of Participants With Annual Influenza Vaccine Among Index Patients	Percent of patients with annual influenza vaccination (between 9/1/22 - 4/1/23) among index patients. Outcomes will be assessed via vaccine data extraction from the electronic health record and external claims and pharmacy data. The index patients must also be an active UCLA Health MyChart user (>= 1 login over the last 12 months from 8/1/22, excluding activity on the user's initial profile activation date). Individuals not affiliated with any primary care practice will be excluded from the primary analysis.	6 months
Number of Participants With Annual Influenza Vaccine Among Pediatric Index Patients	Percent of patients with annual influenza vaccination (between 9/1/22 - 4/1/23) among pediatric index patients. Outcomes will be assessed via vaccine data extraction from the electronic health record and external claims and pharmacy data. The index patients must also be an active UCLA Health MyChart user (>= 1 login over the last 12 months from 8/1/22, excluding activity on the user's initial profile activation date). Individuals not affiliated with any primary care practice will be excluded from the primary analysis.	6 months

Name	Affiliation	Role
Peter Szilagyi, MD, MPH	University of California, Los Angeles	Principal Investigator

Facility	Status	City	State	ZIP	Country	Contacts
University of California, Los Angeles		Los Angeles	California	99095	United States

PubMed Identifier	Type	Citation	Retractions
38497955	Derived	Szilagyi PG, Duru OK, Casillas A, Ong MK, Vangala S, Tseng CH, Albertin C, Humiston SG, Clark E, Ross MK, Evans SA, Sloyan M, Fox CR, Lerner C. Text vs Patient Portal Messaging to Improve Influenza Vaccination Coverage: A Health System-Wide Randomized Clinical Trial. JAMA Intern Med. 2024 May 1;184(5):519-527. doi: 10.1001/jamainternmed.2024.0001.

ID	Title	Description
FG000	Text Fixed R/R Messages With Direct Appointment Schedule Link + Text Pre-Appointment Reminders	Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder via text when they schedule a visit during the study period. Text Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Text Pre-Appointment Reminder: Participants will receive a Pre-Appointment Reminder via text when they schedule a visit during the study period.

Type	Includes Protocol	Includes SAP	Includes ICF	Document Label	Document Date	Document Uploaded Date	Document File Name
Prot	Yes	No	No	Study Protocol	Aug 18, 2022	Mar 26, 2024

Arm/Group Information

ID	Title	Description
BG000	Text Fixed R/R Messages With Direct Appointment Schedule Link + Text Pre-Appointment Reminders	Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder via text when they schedule a visit during the study period. Text Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Text Pre-Appointment Reminder: Participants will receive a Pre-Appointment Reminder via text when they schedule a visit during the study period.
BG001	Text Fixed R/R Messages With Direct Appointment Schedule Link	Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Text Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment.
BG002	Portal Pre-Commitment Prompt, Tailored R/R Messages w/ Direct Scheduling + Pre-Appointment Reminders	Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly by portal based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period. Portal Pre-Commitment Prompt with Tailored R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly by portal based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Portal Pre-Appointment Reminder: Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period.
BG003	Portal Pre-Commitment Prompt With Tailored R/R Messages With Direct Appointment Schedule Link	Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Portal Pre-Commitment Prompt with Tailored R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly by portal based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment.
BG004	Portal Fixed R/R Messages With Direct Appointment Schedule Link + Portal Pre-Appointment Reminder	Participants in this arm will receive up to 3 R/R messages by portal. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period. Portal Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by portal. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Portal Pre-Appointment Reminder: Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period.
BG005	Portal Fixed R/R Messages With Direct Appointment Schedule Link	Participants in this arm will receive up to 3 R/R messages by portal. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Portal Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by portal. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment.
BG006	No R/R Message or Pre-Appointment Reminder	Participants do not receive any flu vaccine R/R message or Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment during the specified flu season.
BG007	Total	Total of all reporting groups

Units	Counts
Participants	BG00043682 BG00143668 BG00221881 BG00321876 BG00421864 BG00521857 BG00687257 BG007262085

Type

Title

Description

Population Description

Reporting Status

Anticipated Posting Date

Parameter Type

Dispersion Type

Unit of Measure

Calculate Percentage

Time Frame

Units Analyzed

Denominator Units Selected

Arm/Group Information

Denominators

Classes

Analyses

Primary

Number of Participants With Annual Influenza Vaccine Among Index Patients

Percent of patients with annual influenza vaccination (between 9/1/22 - 4/1/23) among index patients. Outcomes will be assessed via vaccine data extraction from the electronic health record and external claims and pharmacy data.

The index patients must also be an active UCLA Health MyChart user (>= 1 login over the last 12 months from 8/1/22, excluding activity on the user's initial profile activation date). Individuals not affiliated with any primary care practice will be excluded from the primary analysis.

Posted

Count of Participants

Participants

6 months

ID	Title	Description
OG000	Text Fixed R/R Messages With Direct Appointment Schedule Link + Text Pre-Appointment Reminders	Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder via text when they schedule a visit during the study period. Text Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Text Pre-Appointment Reminder: Participants will receive a Pre-Appointment Reminder via text when they schedule a visit during the study period.
OG001	Text Fixed R/R Messages With Direct Appointment Schedule Link	Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Text Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment.
OG002	Portal Pre-Commitment Prompt, Tailored R/R Messages w/ Direct Scheduling + Pre-Appointment Reminders	Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly by portal based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period. Portal Pre-Commitment Prompt with Tailored R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly by portal based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Portal Pre-Appointment Reminder: Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period.
OG003	Portal Pre-Commitment Prompt With Tailored R/R Messages With Direct Appointment Schedule Link	Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Portal Pre-Commitment Prompt with Tailored R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly by portal based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment.
OG004	Portal Fixed R/R Messages With Direct Appointment Schedule Link + Portal Pre-Appointment Reminder	Participants in this arm will receive up to 3 R/R messages by portal. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period. Portal Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by portal. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Portal Pre-Appointment Reminder: Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period.
OG005	Portal Fixed R/R Messages With Direct Appointment Schedule Link	Participants in this arm will receive up to 3 R/R messages by portal. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Portal Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by portal. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment.
OG006	No R/R Message or Pre-Appointment Reminder	Participants do not receive any flu vaccine R/R message or Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment during the specified flu season.

Units	Counts
Participants	OG00043682 OG00143668 OG00221881 OG003

Title

Denominators

Categories

Title	Measurements
	OG00020689 OG00120570 OG00210374 OG003

Group IDs	Group Description	Statistical Method	Statistical Comment	P-Value	P-Value Comment	Parameter Type	Parameter Value	Dispersion Type	Dispersion Value	Confidence Interval Sides	Confidence Interval %	CI Lower Limit	CI Upper Limit	CI Lower Limit Comment	CI Upper Limit Comment	Estimate Comment	Tested Non-Inferiority	Non-Inferiority Type	Non-Inferiority Comment	Other Analysis Description
OG002 OG003 OG004 OG005 OG006	Comparing the risk of receiving an influenza vaccination					Adjusted Risk Ratio	0.99			2-Sided	95	0.98	1.01			Adjusted risk ratio. These results compare arms which received portal (any type) reminder/recall messages to the arm receiving no reminder/recall messages (control).		Superiority

Primary

Number of Participants With Annual Influenza Vaccine Among Pediatric Index Patients

Percent of patients with annual influenza vaccination (between 9/1/22 - 4/1/23) among pediatric index patients. Outcomes will be assessed via vaccine data extraction from the electronic health record and external claims and pharmacy data.

Posted

Count of Participants

Participants

6 months

ID	Title	Description
OG000	Text Fixed R/R Messages With Direct Appointment Schedule Link + Text Pre-Appointment Reminders	Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder via text when they schedule a visit during the study period. Text Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Text Pre-Appointment Reminder: Participants will receive a Pre-Appointment Reminder via text when they schedule a visit during the study period.
OG001	Text Fixed R/R Messages With Direct Appointment Schedule Link

Arm/Groups

ID	Title	Description
EG000	Text Fixed R/R Messages With Direct Appointment Schedule Link + Text Pre-Appointment Reminders	Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder via text when they schedule a visit during the study period. Text Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Text Pre-Appointment Reminder: Participants will receive a Pre-Appointment Reminder via text when they schedule a visit during the study period.
EG001	Text Fixed R/R Messages With Direct Appointment Schedule Link	Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Text Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by text. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment.
EG002	Portal Pre-Commitment Prompt, Tailored R/R Messages w/ Direct Scheduling + Pre-Appointment Reminders	Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly by portal based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period. Portal Pre-Commitment Prompt with Tailored R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly by portal based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Portal Pre-Appointment Reminder: Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period.
EG003	Portal Pre-Commitment Prompt With Tailored R/R Messages With Direct Appointment Schedule Link	Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Portal Pre-Commitment Prompt with Tailored R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive a pre-commitment prompt message by portal in September. Tailored R/R messages will be sent monthly by portal based on time and place selected by patients (up to 3). R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment.
EG004	Portal Fixed R/R Messages With Direct Appointment Schedule Link + Portal Pre-Appointment Reminder	Participants in this arm will receive up to 3 R/R messages by portal. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period. Portal Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by portal. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Portal Pre-Appointment Reminder: Participants will receive a Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment via portal when they schedule a visit during the study period.
EG005	Portal Fixed R/R Messages With Direct Appointment Schedule Link	Participants in this arm will receive up to 3 R/R messages by portal. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment. Portal Fixed R/R Messages with Direct Appointment Schedule Link: Participants in this arm will receive up to 3 R/R messages by portal. R/R message will be sent with a Direct Appointment Scheduling link and instructions to make a flu vaccine appointment.
EG006	No R/R Message or Pre-Appointment Reminder	Participants do not receive any flu vaccine R/R message or Pre-Appointment Reminder advising them to ask their doctor for the flu vaccine at their upcoming appointment during the specified flu season.

ID	Term
D007251	Influenza, Human
D012141	Respiratory Tract Infections

ID	Term
D007239	Infections
D009976	Orthomyxoviridae Infections
D012327	RNA Virus Infections
D014777	Virus Diseases
D012140	Respiratory Tract Diseases