Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine candidates are being evaluated, with the goal of conferring immunity on the highest percentage of people who receive the vaccine as possible. It is noteworthy that vaccine efficacy depends not only on the vaccine but also on characteristics of the vaccinated. Over the past 30 years, a series of studies has documented the impact of psychological factors on the immune system’s vaccine response. Robust evidence has demonstrated that stress, depression, loneliness, and poor health behaviors can impair the immune system’s response to vaccines, and this effect may be greatest in vulnerable groups such as the elderly. Psychological factors are also implicated in the prevalence and severity of vaccine-related side effects. These findings have generalized across many vaccine types and therefore may be relevant to the SARS-CoV-2 vaccine. In this review, we discuss these psychological and behavioral risk factors for poor vaccine responses, their relevance to the COVID-19 pandemic, as well as targeted psychological and behavioral interventions to boost vaccine efficacy and reduce side effects. Recent data suggest these psychological and behavioral risk factors are highly prevalent during the COVID-19 pandemic, but intervention research suggests that psychological and behavioral interventions can increase vaccine efficacy.

Guided by transactional stress theory, this research investigated the role of appraisals in noninvolved partners’ mental health and health-compromising behaviors after infidelity. Responses from 232 college students who were recently cheated on revealed that negative appraisals (partner blame, self-blame, and causal attribution) had indirect effects on health-compromising behaviors through mental health (depression, anxiety, and distress). Moderated mediation analyses revealed that gender altered the indirect effect of partner and self-blame on health-compromising behaviors through mental health. Men’s health-compromising behaviors did not differ based on their appraisals or mental health. However, women who reported negative appraisals and high levels of mental health consequences engaged in more health-compromising behaviors. These findings suggest that perceptions of a partner’s infidelity are important, and that those perceptions affect noninvolved partners’ mental health and physical health behaviors.

Brief everyday stressors can provoke cardiovascular, hormonal, and immune changes, and the magnitude and duration of these responses can vary considerably. Acute responses to daily stressors can differ widely among individuals experiencing the same stressor, and these physiological responses may not align with stress appraisals. This review highlights individual and dyadic factors that may heighten and prolong stress reactivity, along with their implications for health. We discuss depression, rumination, early life adversity, and social evaluation as individual-level factors and interpersonal stress processes and relationship quality as dyadic-level factors that may influence physiological stress responses. Heightened and prolonged stress reactivity can provide a gateway to the physiological dysregulation that underlies depression and chronic disease, which themselves alter stress reactivity—a vicious cycle. Interventions that may dampen physiological stress reactivity include yoga, meditation, health behaviors (diet, exercise, and sleep), and cognitive behavior therapy.