# Deterioration of COVID-19 vaccine efficacy by antipsychotic medications in schizophrenia patients

## TL;DR

This study finds that antipsychotic medications, especially risperidone, may reduce the effectiveness of COVID-19 vaccines in schizophrenia patients.

## Contribution

The study identifies specific antipsychotics, like risperidone, that may impair vaccine efficacy in schizophrenia patients.

## Key findings

- Schizophrenia patients on risperidone had a 65.6% incidence of COVID-19 despite vaccination.
- Aripiprazole use was associated with 0% incidence of COVID-19 in vaccinated patients.
- Risperidone may impair immune responses and reduce vaccine effectiveness.

## Abstract

It has been previously documented that some antipsychotic medications could deteriorate the protective efficacy of vaccines. Likewise, we have initially observed that a significantly increased number of schizophrenic inpatients became ill irrespective of COVID-19 vaccination compared to healthy hospital workers. Thus, we examined the effects of anti-psychiatric medication on the COVID-19 incidence. A cohort study was conducted with 98 schizophrenia inpatients and 78 control hospital staff members, all of whom received the COVID-19 vaccine between July and September 2021. COVID-19 incidence and vaccine-related side effects were compared between these two groups. The schizophrenia group had a significantly higher incidence of COVID-19 (40.8%) compared to the control group (12.8%) (P < 0.01). In particular, risperidone monotherapy was associated with a significant increase in COVID-19 incidence (65.6%), whereas aripiprazole use was linked to a significant reduction (0%) (P < 0.01). No such difference in COVID-19 incidence was observed in patients using olanzapine. Risperidone administration appears to impair the immune responses and reduce vaccine effectiveness. Further studies with extended subjects and other vaccines are warranted to clarify the anti-vaccine effects associated with risperidone.

The vaccine efficacy in this study is significant because it sheds light on the potential impact of antipsychotic medications, particularly risperidone, on the effectiveness of COVID-19 vaccines in individuals with schizophrenia. The findings suggest that patients treated with risperidone have a significantly higher risk of incidence of COVID-19 despite vaccination, highlighting a possible interference with immune responses. In contrast, aripiprazole appears to have a protective effect, and the combined use of both medications results in an alarming increase in COVID-19 incidence. These results underscore the importance of further investigating the immunological mechanisms underlying these effects, especially through the dopamine receptor activity. Understanding these interactions could lead to more effective vaccination strategies and better healthcare management for patients with schizophrenia, ensuring better protection against COVID-19 and other infectious diseases.