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.