Digital Health Communication and Vaccine Confidence in Mexico Using Aggregated Randomized Brand Lift Studies:...

Area of Science:

• Public Health
• Digital Health Interventions
• Vaccinology

Background:

• Declining vaccine confidence necessitates digital interventions, but real-world evidence from middle-income countries is scarce.
• Meta's Brand Lift Studies (BLS) offer a method to estimate attitudinal shifts from digital content using randomized exposure.
• Mexico's large internet user base provides a suitable context for evaluating digital vaccination campaigns.

Purpose of the Study:

• To assess the impact of 5 digital vaccination campaigns on COVID-19 vaccine confidence in Mexico.
• To analyze changes in key attitudinal constructs, including ad recall, perceived safety, importance, and efficacy.
• To evaluate campaign effectiveness on Facebook and Instagram between 2021 and 2022.

Main Methods:

• Retrospective ecological design analyzing aggregated BLS data.
• Measured outcomes: ad recall, perceived importance, safety, efficacy, and side effect concerns.
• Statistical significance defined by Meta's Bayesian approach (≥2% lift, ≥90% posterior probability).

Main Results:

• Campaigns reached 84.9 million accounts, with all showing significant attitudinal improvements.
• Ad recall increased in 4 campaigns; concerns about side effects decreased in 2.
• Perceived safety, importance, and efficacy improved, particularly in younger users and women.

Conclusions:

• Large-scale digital campaigns can enhance vaccine confidence determinants in middle-income settings.
• Targeted social media strategies improved perceptions, especially among specific demographics.
• While attitudinal shifts were observed, future research should link these to vaccination behaviors.