Recruitment: The proposed study will partner with 30 or more elementary and middle schools
from Utah school districts, as well as private and charter schools in the surrounding area.
All students who attend partnering schools will be enrolled, with parents provided with a
study information sheet/cover letter with details about the study and information on how to
opt out. Staff at the participating schools/districts who wish to participate will also be
enrolled and receive the same information sheet/cover letter and opt-out information.

Intervention: Randomization of parent/student and staff participants will consist of two
phases, both taking placed upon enrollment in the study. Phase 1 will consist of assigning
participants to text messaging or to usual care groups. The Phase 2 randomization will take
place among participants in the TM condition. They will be assigned a Phase 2 condition of
continued TM or TM + health navigator (HN), which they will received during intervention
cycles in which they are evaluated as non-compliant.

Phase 1

Participants included in Phase 1 are those who did not opt-out of the study. Participants
eligible for Phase 1 Randomization will either be assigned to 1) Usual Care (control,
approximately 20% of participants) or 2) Text Messages (TM, approximately 80% of
participants).

- Usual Care- Participants will only receive public service announcement-type messaging on
COVID-19 testing every 3 weeks (e.g., recommendation to obtain COVID-19 testing if
exposed or experience symptoms; information on testing options through the school or
district).

- TM consists of a text message prompt asking if a participant has COVID-19 symptoms or if
a participant has been exposed to a person that has tested positive for COVID-19. If a
participant responds yes, they will receive a TM prompt for immediate testing and to
re-test. Participants will be provided with information on testing options for COVID-19.
After 24 hours, the participant will be asked if they tested and what their results are.
After 3 days, participants will be prompted to re-test.

Phase 2

For participants in the TM condition, the Phase 2 condition will be randomly assigned upon
enrollment. Participants will receive their Phase 2 condition if they are non-compliant with
the TM intervention. Participants will be evaluated as non-compliant if they had reported
symptoms or contact and then stop responding to text messages or respond that they did not
test. Participants will be randomized to 1) TM or 2) TM plus health navigator (TM+HN).

- TM will continue to consist of prompts and reminders on COVID-19 testing options.

- TM+HN consists of continued text messages about COVID-19 testing options with the
addition of a brief telephone call from a health navigator (HN). These calls will be
conducted using Motivation and Problem Solving (MAPS). MAPS is an empirically validated
proactive coaching approach used to address barriers and motivate participants to
utilize testing options if they are experiencing COVID-19 symptoms or have been exposed
to someone that has tested positive for COVID-19.

Assessments: The study team will collect survey data from students, staff members and parents
at pre- and post-intervention as well as throughout the trial. COVID-19 test results of
participants will be collected through self-report as well as through results reported to the
"Ellume" testing app. Additionally, the study team will conduct stakeholder interviews with
students, parents, and staff on ways to improve the interventions to better meet their needs
and preferences.

Addendum to study allocation ratio: Change of allocation for participants eligible for Phase
1 Randomization

• The study's allocation ratio was changed on 7/20/22. The original allocation ratio for
Phase 1 of the study was 80% text message (TM) to 20% control. The new allocation ratio for
Phase 1 was 50% TM to 50% control. The reason for the change in allocation ratio is that the
study team observed low numbers of participants in TM and control groups reporting any
COVID-19 testing. Thus, in order to optimize statistical power to be able to compare TM vs.
control groups in end-of-study analyses, the allocation ratio was changed to the 1:1
allocation. For schools that were enrolled in the study prior to this allocation ratio
change, individuals in that school who had already been assigned a study condition maintained
their original assignment. To account for this change in allocation, we will adjust for the
allocation ratio for when the participant was randomized, within the model.

Addendum to outcome measures timeline: Change of survey timeline of outcomes for eligible
participants

• The survey distribution timeline was changed 9/27/22. The 6-month survey was not
distributed (due to an electronic distribution error) and the timing of this survey was
changed to 9 months post intervention enrollment. Additionally, the 1-month survey was only
distributed in Year 1 of the study. Newly enrolled participants in Year 2 (as of 8/1/22) did
not receive the 1-month survey. The purpose of the 1-month survey was to complete an early
assessment of the intervention to determine if any changes were needed based on participant
feedback, and thus was not needed in the second year of the study. Enrolled participants that
did not complete the baseline survey were sent a follow up survey at the end of the study to
collect demographic and other outcomes data. A final survey distributed at the end of the
study was also added in order to assess accessibility, feasibility, and other outcomes.