COVID-19(4) Anxiety(1) physician–patient trust(1) Positive intervention(1) Wellbeing.(1) Preventive behaviors.(1) Health threat(1) enjoyment(1) social media.(1) control group(1) Health(1) COVID-19 fear(1) smoking(1) eHealth(1) public health emergency(1) Resilience(1) keyworkers(1) Stress(1) intervention use.(1) machine learning-based sentiment analysis(1) positive mental health(1) frontline workers(1) Extended parallel process model(1) Thematic analysis.(1) interest(1) fear(1) Quarantine.(1) coronavirus(1) cv19heroes(1) lockdown(1)