COVID-19 vaccination rates lower among those with schizophrenia despite increased risks

Individuals with schizophrenia had lower COVID-19 vaccination rates than the general population despite having higher hospitalization and mortality risk, according to results of a longitudinal cohort study.

“In two cross-sectional studies published in 2021, we reported an association between schizophrenia and COVID-19 hospitalization and mortality, as well as an association between schizophrenia and lower odds of being vaccinated,” Dana Tzur Bitan, PhD, of the department of behavioral sciences at Ariel University in Israel, and colleagues wrote in The Lancet Psychiatry. “Nonetheless, to the best of our knowledge, no study has previously assessed the longitudinal trends of these effects over time in this patient population. As such, this study aimed to provide a longitudinal evaluation of hospitalization, mortality and vaccination, as well as to assess outcomes before and after vaccination.”

The researchers evaluated pre- and post-vaccination outcomes among 25,539 people with schizophrenia compared with 25,539 controls (of total participants, 61% men; mean age, 51.94 years) in Israel up to April 30. They conducted Cox proportional hazard regression models and Kaplan-Meier analyses to evaluate longitudinal trends. They obtained data via databases of Israel’s largest health care organization. A total of 75.9% of the sample was from the general Jewish population, 19.1% from the Arab population and 5.1% from the Jewish Ultraorthodox population.

Among the overall study population, 356 (0.7%) people had been hospitalized, 133 (0.3%) had died and 27,400 (53.6%) had been vaccinated. Those with schizophrenia had increased risk for COVID-19 hospitalization (HR = 4.81; 95% CI, 3.57-6.48) and mortality (HR = 2.52; 95% CI, 1.64-3.85), as well as a more significant decline in survival as time progressed. Those in the control group exhibited a sharper incline in likelihood of vaccination. Significant predictors of vaccination rates in the schizophrenia group included medical comorbidity of diabetes, hypertension, obesity or ischemic heart disease (all, P < .0001); however, these did not serve as significant predictors among the control group. Although hospitalization and mortality disparities remained higher among people with schizophrenia who had not been vaccinated compared with controls (incidence rate difference = 6.2 and 3.2, respectively), they substantially declined among fully vaccinated groups (incidence rate difference = 1.1 and –0.9, respectively).

“This study did not control for psychiatric clinical factors such as medication exposure, duration of illness or inpatient status,” Bitan and colleagues wrote. “Future studies should assess the predictive effect of these factors on vaccination rates. Taken together, the results stress the importance of facilitating better prevention strategies for individuals with severe mental illness, to provide better care for patients suffering from severe mental illnesses.”

In a related editorial, Livia J. De Picker, MD, a psychiatrist and postdoctoral researcher at the University Psychiatric Hospital Duffel in Belgium, noted that the pandemic provides a “unique opportunity” for certain psychiatric research opportunities.

“The pandemic offers a unique opportunity to study the individual (eg, clinical predictors of at-risk groups), mental health care (eg, treatment setting) and macro-organizational (eg, country health care system) determinants of COVID-19 outcomes and vaccine uptake among patients with mental disorders,” De Picker wrote. “I consider this a priority in the research agenda of mental health care researchers worldwide. Evidence is the prerequisite for effective action, during and after the COVID-19 pandemic.”