Response to the COVID-19 Vaccine in Persons with Schizophrenia and Other Serious Mental Illnesses

Background: The COVID-19 pandemic, caused by the SARS-2 Coronavirus, poses particular challenges to persons with schizophrenia and other serious mental illnesses (SMI) because of their elevated rate of medical conditions which are risk factors for severe COVID-19 illness and their reduced access to monetary and other societal resources. Early reports indicated that persons with schizophrenia who were hospitalized were more likely to die from COVID-19 than other persons. However, it is uncertain if persons with SMI are more vulnerable to infection with SARS-Cov-2. It is also unclear what is the acceptance rate of COVID-19 vaccinations among persons with SMI. There are also few data available about the immune response to COVID-19 vaccines in this population. Methods: Participants were assessed between Dec 12, 2020 – Feb 22, 2022, before and after receiving COVID-19 vaccine doses. All were previous participants in our studies about the association between infection and SMI. At each assessment, information was obtained about the dates and type of COVID-19 vaccine received and experiences of COVID-19 infection. All participants had a blood sample drawn; multiplex chemilumnescence assays were used to measure IgG antibodies to 3 SARS-2 virion spike and nucleoproteins based on the Wuhan strain. We also measured antibodies to the spike proteins of the variant Omicron strain. Data were analyzed with mixed effects models with relevant covariates including age, BMI, cigarette smoking and type of vaccine. Results: A total of 315 samples were obtained from 176 persons (28 schizophrenia, 51 bipolar disorder, 80 major depressive disorder, and 17 non-psychiatric comparison persons). Mean age was 37.3 (± 14.0) years; 69 (39%) were male, and 115 (65%) White. A total of 34 (19%) had evidence of a natural COVID-19 infection assessed from laboratory measures; the rate was not significantly different among the diagnostic groups. In terms of receipt of the vaccine, results of a Cox proportional hazards Kaplan Meier failure curve indicated that the non-psychiatric comparison group obtained the vaccine earliest; all of the psychiatric groups received the first dose significantly later (STAT, p= 041; STAT, p< .005; STAT, p< .001, respectively). Results were similar for the receipt of complete doses of the vaccine. The levels of antibodies to the SARS-COV-2 spike protein following immunization were compared among the groups. While the groups were similar in the level of antibodies following the complete regimens, the immune response to the vaccine strain was delayed in individuals with schizophrenia as evidenced by decreased levels of antibodies following the first dose of two dose regimens (STAT, p=006); however, this group attained levels after the second doses which were not different from the controls. However, individuals with schizophrenia had significantly lower levels of antibodies to the omicron variant (p=.012) indicating lower levels of protection against mutated forms of SARS-2. Discussion: Persons with SMI received COVID-19 vaccines later than those in the comparison group. In addition, individuals with schizophrenia mount a lower response initially to the COVID-19 vaccine and generate lower levels of antibodies associated with protection against viral genetic variants. These findings raise a concern about the vulnerability of persons with SMI to new variants of the SARS-Cov-2 virus in the ongoing pandemic.