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Effect of Personalized Messages Sent by a Health System's Patient Portal on Influenza Vaccination Rates: a Randomized Clinical Trial.



Adult influenza vaccination rates are low. Tailored patient reminders might raise rates.


Evaluate impact of a health system's patient portal reminders: (1) tailored to patient characteristics and (2) incorporating behavioral science strategies, on influenza vaccination rates among adults.


Pragmatic 6-arm randomized trial across a health system during the 2019-2020 influenza vaccination season. The setting was one large health system-53 adult primary care practices.


All adult patients who used the patient portal within 12 months, stratified by the following: young adults (18-64 years, without diabetes), older adults (≥65 years, without diabetes), and those with diabetes (≥18 years).


Patients were randomized within strata to either (1) pre-commitment reminder alone (1 message, mid-October), (2) pre-commitment + loss frame messages, (3) pre-commitment + gain frame messages, (4) loss frame messages alone, (5) gain frame messages alone, or (6) standard of care control. Patients in the pre-commitment group were sent a message in mid-October, asking if they planned on getting an influenza vaccination. Patients in loss or gain frame groups were sent up to 3 portal reminders (late October, November, and December, if no documented influenza vaccination in the EHR) about importance and safety of influenza vaccine.

Main measures

Receipt of 1 influenza vaccine from 10/01/2019 to 03/31/2020.

Key results

196,486 patients (145,166 young adults, 29,795 older adults, 21,525 adults with diabetes) were randomized. Influenza vaccination rates were as follows: for young adults 36.8%, for older adults 55.6%, and for diabetics 60.6%. On unadjusted and adjusted (for age, gender, insurance, race, ethnicity, and prior influenza vaccine history) analyses, influenza vaccination rates were not statistically different for any study group versus control.


Patient reminders sent by a health system's patient portal that were tailored to patient demographics (young adults, older adults, diabetes) and that incorporated two behavioral economic messaging strategies (pre-commitment and loss/gain framing) were not effective in raising influenza vaccination rates.

Trial registration

This trial was registered with (NCT04110314).

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