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Implementation of a chatbot based on behavioral strategies to promote the continuity of vaccination against COVID-19 in the province of Chaco: a randomized controlled trial

General Information

Project description

Despite the overwhelming medical evidence on the protection offered by the second, third and fourth doses of the Covid-19 vaccine, the acceptance of these doses remains low despite the existing supply. The problem is likely because there are currently no reminders in the province of Chaco, Argentina. This makes it difficult for residents to know if they are eligible for the next dose of the COVID-19 vaccine and where to access it.

Booster vaccination is associated with a lower risk of mortality from COVID-19. Therefore, increasing the acceptance of reinforcements can save the lives of those receiving the reinforcement. Also, by reducing pressure on healthcare providers, an increased booster vaccination may have health benefits for other people (ie, not just those receiving the vaccine).
This is a three-arm, individual-level randomized controlled trial (RCT) to test whether a COVID-19 vaccination messaging Chatbot in Chaco, Argentina, can increase vaccine uptake among those who do not have received their 'next dose' (ie a second, third or fourth dose) of the vaccine.

Personalized messages were sent to participants via a Whatsapp chatbot informing people that they are eligible for the next dose, encouraging vaccination, and providing planning guidance to receive their next dose of the Covid-19 vaccine.

Detailed information


Chatbot intervention results in increased "next dose" vaccination rate, compared to simple non-chatbot messages and no messages at all.

This is a randomized controlled trial.
active branch:
(1) Personalized messages through the chatbot
Comparison/control conditions:
(1) Pure control, where the participants do not receive a message.
(2) Simple message control, where participants receive a single message that is not a chat bot promoting vaccination.
Randomization unit: Single
Method: Simple randomization.
All groups finally receive the most effective message at the end of the study.

Dependent variables

Vaccination rate of the “next dose” in the province of Chaco, Argentina.


We will test the effect of the chatbot by comparing the proportion of people who have received a Covid-19 vaccination within a two-week period of receiving the WhatsApp chatbot message between the two groups, using data from the MoH.

Who is behind the project?

Institution: Other
Team: Behavioral Sciences and Public Policy Unit

Project status:


Methodology: Experiment
Could you self-grade the strength of the evidence generated by this study?: 1

What is the project about?

Policy area(s): Health, Vaccines
Topic(s): 一 Other
Behavioural tool(s): Personalization, Reminders

Date published:

23 February 2023

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