The COVID-19 pandemic has led to a mis/disinformation ecosystem that promotes divergentviews of vaccine efficacy, as well as the legitimacy of science and medicine. Individualsare confronted with vaccine-related information from a multitude of sources, posing achallenge to identifying inaccurate information. COVID-19 vaccine uptake is lower amongpeople with anxiety and depression than in the general population, due in part to higherlevels of vaccine hesitancy. The prevalence of anxiety and depressive symptoms among USadults increased significantly during the COVID pandemic and has remained elevated.Interventions capable of mitigating the impact of vaccine hesitancy andmis/disinformation among undervaccinated people with anxiety or depression are thereforean urgent priority. Emerging evidence suggests that reasons for vaccine hesitancy and theimpact of conventional vaccination messaging differ between those with and without mentalhealth symptoms. There may also be added challenges overcoming logistical barriers tovaccination for people with anxiety or depressive symptoms.The investigators aim to determine the effectiveness of two different brief digitalintervention strategies compared with conventional public health messaging for increasingvaccine uptake in undervaccinated adults with and without anxiety or depressive symptoms.Attitudinal inoculation is a brief, scalable strategy that leverages the power ofnarrative, values, and emotion to strengthen resistance to mis/disinformation and reducehesitancy. Though this approach has been shown to decrease COVID-19 vaccine hesitancyamong US adults, the extent to which this approach increases COVID-19 vaccination remainsunknown. Cognitive-behavioral therapy (CBT) is an evidence-based intervention for anxietyand depression. However, the efficacy of incorporating CBT-informed messaging in avaccine promotion intervention has not been tested. The investigators hypothesize thatboth attitudinal inoculation and CBT-style communication will be more effective thanconventional public health messaging to increase COVID-19 vaccination. The investigatorsalso hypothesize that the CBT-informed intervention will be more effective than theattitudinal inoculation intervention for increasing COVID-19 vaccination amongparticipants with symptoms of anxiety or depression.