SMS Campaign to Increase COVID-19 Vaccine Take-up in Tanzania

Last registered on November 30, 2022

Pre-Trial

Trial Information

General Information

Title
SMS Campaign to Increase COVID-19 Vaccine Take-up in Tanzania
RCT ID
AEARCTR-0009832
Initial registration date
November 28, 2022

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
November 30, 2022, 4:37 PM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Locations

There is information in this trial unavailable to the public. Use the button below to request access.

Request Information

Primary Investigator

Affiliation

Other Primary Investigator(s)

PI Affiliation
Institute of Social Works (ISW)
PI Affiliation
Economic and Social Research Foundation
PI Affiliation
Economic and Social Research Foundation (ESRF)

Additional Trial Information

Status
On going
Start date
2022-11-24
End date
2023-05-08
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
Abstract
What messaging will convince Tanzanians to get a COVID-19 vaccine? We propose to use a randomized placebo-controlled trial, to evaluate an SMS campaign targeting Tanzanian mobile phone subscribers with two different SMS content aimed at increasing vaccine take up. We hypothesize different mechanisms by which Tanzanians may be induced to agree to get a COVID-19 vaccine including (1) altruism for others (empathy); and (2) COVID-19’s long term health impacts (Self interest). A placebo group of mobile subscribers will receive an SMS unrelated to the aforementioned interventions. We intend to share the effective messages, in addition to information on where to access vaccinations, with everyone in our sample no more than 3 months after treatment. Our proposed work is expected to inform literature on the social science of persuasion more broadly but specifically as it relates to persuading adults to take up health interventions, in particular, a COVID-19 vaccine. We expect our results to be highly informative not only for Tanzanian public health policy but also more broadly by providing precise estimates of precise content that may help increase COVID-19 vaccine take up and accelerate an end to this pandemic.
External Link(s)

Registration Citation

Citation
Fille, Christina et al. 2022. "SMS Campaign to Increase COVID-19 Vaccine Take-up in Tanzania." AEA RCT Registry. November 30. https://doi.org/10.1257/rct.9832-1.0
Sponsors & Partners

There is information in this trial unavailable to the public. Use the button below to request access.

Request Information
Experimental Details

Interventions

Intervention(s)
We propose sending SMS messages of varying content in a randomized placebo-controlled experiment. Our experiment will be based on two (2) treatment arms which will receive two (2) different text message content and one placebo group which will receive SMS content on some other non-public health issue unrelated to COVID-19.

Treatment 1 (T1): We call this treatment the EMPATHY treatment, where mobile phone subscribers in this arm will receive an SMS message emphasizing one’s increased potential contribution to harming others through exposing them to COVID-19, in the absence of vaccination.

Treatment 2 (T2): We call this treatment the SELF - INTEREST treatment, where mobile phone subscribers in this arm will receive an SMS message on adverse long-term effects of COVID-19 infection.

Placebo group (C), where mobile phone subscribers in this arm will receive an SMS message on some other non-public health issue unrelated to COVID-19.
Intervention Start Date
2022-11-30
Intervention End Date
2023-01-03

Primary Outcomes

Primary Outcomes (end points)

a. Self-reported vaccination status. This will be assessed by a follow up survey question “Have you received the full dose of any COVID-19 vaccine?”

b. Household members’ vaccination status. This will be assessed by a follow up survey question “How many of your household members have received the full dose of any COVID-19 vaccine?”

c. Objectively verified vaccination status: “Please provide either your NIDA (national ID), passport number, voter ID, or other ID number or your full name that you used when you registered and received the COVID-19 vaccine.”

d. Self-reported intent to vaccinate. This will be assessed by a follow up survey question “Do you intend, in the next 12 months, to receive the full dose of any COVID-19 vaccine?”
e. Household members’ intent to vaccinate. This will be assessed by a follow up survey question “How many of your household members have expressed intentions, in the next 12 months, to receive the full dose of any COVID-19 vaccine?”
f. Subjective trust on COVID-19 vaccines: From a scale of 1 to 10 where 10 is complete trust and 1 is no trust, how much do you trust the COVID-19 vaccines?
g. Self-reported compliance on wearing masks. This will be assessed by a follow up survey question “In the last 14 days, how often did you wear a mask whenever you were in public spaces with other people?


Heterogeneity Analysis.

According to Africa CDC vaccine hesitancy survey of March 2021, those who are more skeptical towards COVID-19 vaccines tend to be female, young people, those who are unemployed and those living in cities and therefore, with respect to our treatments we expect female, young individuals, unemployed and those living in cities to react less to our treatments. Moreover, with respect to our EMPATHY and SELF-INTEREST treatments, we expect women to be more empathetic and have differential discount factors of time relative to men (Falk, et al., 2018). Similarly, because younger people have more time relative to older people, we expect their preferences for time but also others to differ. Finally, individuals who are unemployed and/or rural residents will have relative lower incomes than the employed/urban dwellers and we also know that incomes matter for risk preferences. Hence, we anticipate sex, age, employment status and urban residency will display heterogeneous effects. To capture this, we will run the analysis by regressing outcomes on an interaction between the treatment dummy and the characteristic.

We also going to do a “change-from-baseline” analysis for no more than 4,766 respondents for the 6 outcomes we currently have some data on for each of the six (6) outcomes along with covariates included as well.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
We propose to use a randomized placebo-controlled experiment. There will be two treatments (T2 and T2) and placebo group. Randomization will ensure the balance of observable and non-observable characteristics between control and experiment groups and therefore any difference between them in our outcomes of interest will be due to our proposed intervention.
Experimental Design Details
Not available
Randomization Method
Randomization will be done in office by a computer
Randomization Unit
Mobile phone subscribers
Was the treatment clustered?
No

Experiment Characteristics

Sample size: planned number of clusters
None
Sample size: planned number of observations
12,000 mobile phone subscribers.
Sample size (or number of clusters) by treatment arms
The unity of analysis is individuals’ phone subscribers from IPSOS database. As research budget allow for 12,000 sample size, which is powered for our purpose. We set the sample sizes as to 4,500; 4,500; and 3,000 for T1; T2; and Placebo, respectively
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
Introduction Throughout the following power calculations of the pairwise comparisons between T1 and Placebo; T2 and Placebo; and T1 vs T2 we begin by setting the sample sizes as to 4,500; 4,500; and 3,000 for T1; T2; and Placebo, respectively. We also begin by setting alpha = 0.05 and power = 0.8. In accounting for multiple comparison bias, we divide alpha = 0.05/7 = 0.00714286 for our seven (7) outcomes. Outcome 1: Actual Vaccination Rates We begin by first outlining the assumptions on baseline values of two outcome variables. The first is on actual vaccination rates in Tanzania, which we set at 7%. We set it at 7% because Our World In Data’s latest data shows that as a percentage of the adult population, only about 6.6% of adult Tanzanians are vaccinated as of this writing. Power calculations for a two-sample proportions chi2 test shows that the MDE for the actual vaccination rate outcome given an assumed 7% rate of vaccinations among adult Tanzanians is 1.79% points (T1/T2 vs Placebo). This MDE increases to 2.29% points when accounting for multiple comparisons across our 7 outcomes (alpha = 0.05/7 = 0.00714286). Comparing T1 to T2 assuming a baseline of 8.06% with alpha = 0.05, the MDE is 1.68 % points, which increases to 2.14 % points. When accounting for multiple comparisons (alpha = 0.05/7 = 0.00714286). Outcome 2: Vaccine Hesitancy/Confidence Next, we continue onto the vaccine hesitancy/confidence outcome. We set the baseline percentage of vaccine hesitancy/confidence for Tanzania at 41%. This is informed by Africa’s CDC February 2021 (Figure 2.3.2 on page 10 [pdf page 11]) on survey results from across 15 African countries, excluding Tanzania, which has the Democratic Republic of Congo (DRC) as hosting the most vaccine hesitant population where only about 59% of respondents expressed willingness to accept a new COVID19 vaccine. Please note that surveying likely occurred before any public news of actual successfully-tested COVID19 vaccines being made available to the wider public. Nevertheless, we assume a baseline level of 41% as our baseline on vaccine hesitancy/confidence, which is likely a lower limit to actual COVID19 vaccine hesitancy/confidence in Tanzania were it to be measured today. Power calculations for a two-sample proportions chi2 test shows that the MDE for the COVID19 vaccine hesitancy outcome given an assumed 41% vaccine hesitancy/confidence among adult Tanzanians, is 3.27% points (T1/T2 vs Placebo). This MDE increases to 4.12% points when accounting for multiple comparisons across our 7 outcomes (alpha = 0.05/7 = 0.00714286). For T1 vs T2, with alpha = 0.05 with a baseline of 44% the MDE is 2.94 % points, which after accounting for multiple comparisons (alpha = 0.5/7 = 0.00714286) increases to 3.71% points.
Supporting Documents and Materials

There is information in this trial unavailable to the public. Use the button below to request access.

Request Information
IRB

Institutional Review Boards (IRBs)

IRB Name
National Institute for Medical Research
IRB Approval Date
2022-09-02
IRB Approval Number
NIMR/HQ/R.8a/Vol.IX/4091
Analysis Plan

There is information in this trial unavailable to the public. Use the button below to request access.

Request Information