Preventive Behavior and Factors Associated with COVID-19 in Fully Vaccinated Adults: Cross-sectional Study

Abstract

Objective: Understanding the factors influencing preventive behavior in vaccinated populations is essential for pandemic preparedness. This study assessed protective behaviors among adults vaccinated against COVID-19 in Guaramiranga, a small municipality in Ceará, Brazil, with approximately 5,073 inhabitants. Guaramiranga became the first municipality in the state to fully vaccinate its registered population, beginning on January 20, 2021. Method: A cross-sectional analytical study using structured digital questionnaires was conducted from September 2021 to December 2022. Outcome variables included self-reported adherence to hand hygiene, mask use, distancing, and isolation, analyzed in relation to sociodemographic characteristics, health conditions, and knowledge about SARS-CoV-2. Result: Among 2,830 participants (53.9% female; median age 39), the most frequent behaviors were handwashing (65.3%), mask use when leaving home (63.8%), and continued use post-vaccination (59.7%). Women and younger adults reported higher adherence (p < 0.05). Lower education was associated with greater isolation and distancing (p < 0.05), underscoring social determi-
nants in health behavior. Individuals with chronic conditions and better knowledge about prevention were significantly more adherent. Conclusion: Despite full vaccination, most participants maintained preventive measures, which may
have contributed to low local hospitalization and mortality rates. These findings reinforce the importance of tailored
public health messaging and local preparedness efforts, particularly in socially diverse communities.