There is limited data on association of psychosis with the use of vaccines. There are few case reports of development of psychosis after administration of vaccines for rabies (Bhojani et al., 2014), yellow fever (Romeo et al., 2021), smallpox, typhus and influenza. With respect to COVID-19 vaccine, few published case report has documented the association of psychosis with the use of vaccine and some of the reports indicate that psychosis could be an outcome of autoimmune encephalitis (Reinfeld et al., 2021; Roberts et al., 2021; Takata et al., 2021; Yesilkaya et al., 2021).
Very few reports are available showing COVID-19 vaccine induced psychosis. Studies have shown that SAR-CoV-2 is known to trigger a powerful immune response, which includes the release of large amounts of pro-inflammatory cytokines. It is hypothesized that psychosis may be related to rapid increase in the proinflammatory response and activated autoimmune mechanism (Yesilkaya et al., 2021). The MRI findings of tiny T2/FLAIR hyperintensities in deep white matter in bilateral fronto-parietal lobes in the index case could be indicators of the endothelial and autoimmune activation, as seen in autoimmune encephalitis.
It has also been hypothesized that COVID-19 may increase the risk of psychosis by triggering the cytokine storm. It can be hypothesized that the cytokine storm with elevated serum concentrations of IL-6, IL-8 and IL-2 can affect the levels of monoamine neurotransmitters, i.e., lead to increase reuptake of dopamine, serotonin, and norepinephrine, and influence on the release of neurotransmitters. Cytokines may also result in increased kynurenic acid with resultant NMDA receptor hypofunction, increased pyramidal firing, increased inhibitory activity of the nucleus accumbens, and decreased inhibitory tone over the ventral tegmental area dopaminergic neurons and increased production of dopamine. The increase in the dopamine may be responsible for psychosis.
Schizophrenia has also been related to pro- inflammatory status (Goldsmith et al., 2016). The administration of vaccine elicits an immune response including a cellular immune reaction which leads to T-helper cells production of pro-inflammatory cytokines.
The catatonic features in the index case could be due disruption of the associative functions, especially the connectivity of frontal lobes with parietal cortex and motor areas, contributing to the akinetic form of catatonia (Ellul and Choucha, 2015). Though the risk of developing psychosis after covid vaccine is very rare (Reinfeld et al., 2021), medical professionals need to be sensitized about this for early recognition and benefits of the patient.