A Seizure After COVID-19 Vaccination in a Patient on Clozapine

Central nervous system manifestations following vaccination against COVID-19

Coronavirus disease 2019 (COVID-19) vaccination has become the most effective countermeasure in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. However, vaccination is associated with side effects. This narrative review focuses on central nervous system (CNS) manifestations following COVID-19 vaccination and provides a summary of the potential underlying mechanisms and methods of diagnosis and management of the vaccination-related CNS manifestations. Headache, myalgia, optic neuritis, seizure, multiple sclerosis, acute disseminated encephalomyelitis and encephalitis, delirium, acute transverse myelitis, and stroke have been reported after COVID-19 vaccination. Constant headache and myalgia are common manifestations that may necessitate further clinical investigation for stroke. To limit consequences, it is imperative to follow standard treatment protocols for each neurological disorder following COVID-19 vaccination. Immunosuppressive medication can be helpful in the treatment of seizures following vaccination since the immune response is involved in their etiology. Clinicians should be aware of the manifestations after COVID-19 vaccination to respond promptly and effectively. Clinical guidelines for the management of CNS manifestations following COVID-19 vaccination are in high demand and would be useful in each new SARS-CoV-2 variant pandemic.

A Rapid Review of the Effects of the COVID-19 Vaccine Among Individuals Taking Clozapine

BACKGROUND

The COVID-19 pandemic prompted the rapid development of vaccines to combat the virus. Several COVID-19 vaccines have proven effective in preventing infection, hospitalization, and death. Vaccination has been especially recommended for vulnerable populations, such as individuals with psychiatric illnesses who face increased risks due to comorbidities and socioeconomic factors. This rapid review identifies and analyzes the effects of COVID-19 vaccines among individuals taking clozapine.

METHODS

The review included articles from PubMed, OVID, Clinical Key, Web of Science, and Google Scholar, published between September 2020 and December 2023. Inclusion criteria were peer-reviewed journals, English language, patients on clozapine receiving a COVID-19 vaccine, and documented vaccine-related adverse effects.

RESULTS

Twelve articles were included, consisting of 8 case reports, 1 cross-sectional study, and 3 prospective observational studies, involving 298 subjects, with 9 subjects from case reports. After the first vaccine dose, 27 of 248 subjects experienced adverse effects, with 1 case report advising a temporary halt and dose reduction of clozapine. The subject in this case was admitted in a delirious state 4 days after vaccination with repeated falls and urinary incontinence; active infectious and neurologic etiologies were ruled out. Second dose data were available for 261 subjects, with 31 reporting adverse effects. Adverse effects included hematological changes, delirious state, seizures, and fever.

CONCLUSIONS

The review suggests that individuals on clozapine receiving COVID-19 vaccines may experience adverse effects. Clozapine levels and immune system interactions should be monitored in these cases.

Association of New-Onset Seizures With SARS-CoV-2 Vaccines: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Importance

Seizures have been reported as an adverse effect of the SARS-CoV-2 vaccine. However, no study has answered the question of whether there is any association between seizures in the general population and COVID-19 vaccination.

Objective

To evaluate the seizure incidence among SARS-CoV-2 vaccine recipients compared with those who received a placebo.

Data Sources

A systematic search of MEDLINE (via PubMed), Web of Science, Scopus, Cochrane Library, Google Scholar, review publications, editorials, letters to editors, and conference papers, along with the references of the included studies from December 2019 to July 7, 2023.

Study Selection

Randomized clinical trials (RCTs) reporting seizure incidence with SARS-CoV-2 vaccination were included.

Data Extraction and Synthesis

This study is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses framework and used the Mantel-Haenszel method with random- and common-effect models. The risk of bias of the studies was assessed using the Cochrane assessment tool for RCTs.

Main Outcomes and Measures

The outcome of interest was new-onset seizure incidence proportion compared among (1) SARS-CoV-2 vaccine recipients and (2) placebo recipients.

Results

Six RCTs were included in the study. Results of the pooled analysis comparing the incidence of new-onset seizure between the 63 521 vaccine and 54 919 placebo recipients in the 28-day follow-up after vaccine/placebo injection showed no statistically significant difference between the 2 groups (9 events [0.014%] in vaccine and 1 event [0.002%] in placebo recipients; odds ratio [OR], 2.70; 95% CI, 0.76-9.57; P = .12; I2 = 0%, τ2 = 0, Cochran Q P = .74). Likewise, in the entire blinded-phase period after injection, with a median of more than 43 days, no significant difference was identified between the vaccine and placebo groups regarding incident new-onset seizure (13/43 724 events [0.03%] in vaccine and 5/40 612 [0.012%] in placebo recipients; OR, 2.31; 95% CI, 0.86-6.23, P = .10, I2 = 0%, τ2 = 0, Cochran Q P = .95).

Conclusions and Relevance

According to this systematic review and meta-analysis, there was no statistically significant difference in the risk of new-onset seizure incidence between vaccinated individuals and placebo recipients.

Vaccination and clozapine use: a systematic review and an analysis of the VAERS database

In the context of COVID-19 concerns related to the potential interactions between clozapine and vaccination arose. With the ultimate goal of deriving recommendations for clinical practice, we systematically reviewed the current evidence regarding altered vaccine effectiveness in clozapine-treated patients and safety aspects of vaccination, such as haematological changes and the impact of vaccines on clozapine blood levels, in clozapine-treated patients. A systematic PRISMA-conform literature search of four databases (PubMed, PsycINFO, EMBASE and Cochrane Library) complemented by a case-by-case analysis of the Vaccine Adverse Event Reporting System (VAERS) database was performed. We then systematically appraised the joint evidence and tried to derive recommendations for clinical practice. 14 records were included in this analysis. These records consisted of 5 original articles and 9 case reports. Among the original articles, two studies provided data on the association between clozapine use and antibody responses to vaccination, both indicating that clozapine use in schizophrenia may be associated with reduced levels of immunoglobulins. Additionally, three studies examined vaccine safety in clozapine-treated patients, with no clinically significant adverse effects directly attributable to the interplay between vaccinations and clozapine. VAERS Analysis encompassed 137 reports and showed no consistent evidence of an increased risk for clozapine blood level increases or adverse events. We found no evidence indicating that clozapine impairs the effectiveness of vaccines. Moreover, no serious safety concerns seem to apply when patients on clozapine are receiving vaccines. However, it is crucial to acknowledge that data on the interaction between clozapine and vaccines remain limited.

Electroencephalographic findings post-COVID-19 vaccination: A systematic review of case reports and case series

A number of different neurological complications have been reported following vaccination against the coronavirus disease 2019 (COVID-19). Electroencephalogram (EEG) is one of the modalities used to evaluate the neurological complications of diseases. The aim of the present study was to identify the EEG changes in participants vaccinated against COVID-19. PubMed, Scopus, Web of Science, medRxiv, and Google Scholar were searched up to 1 September 2022, with terms related to COVID-19 vaccines, EEG, neurological signs/symptoms, or neurological disorders. All case reports and case series were included if the participants had received at least one dose of a COVID-19 vaccine and a post vaccination EEG report was also reported. We used the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for case reports and case series to appraise the methodological quality of the included studies. Thirty-one studies were included, which were comprised of 24 case reports and seven case series and a total of 36 participants. Generalised slowing and non-convulsive focal status epilepticus were the most common EEG findings post-COVID-19 vaccination. The most frequent symptoms were headache, fatigue, generalised weakness, and vomiting. In addition, the most common signs were encephalopathy, post-ictal phases, and confusion. Encephalitis, acute disseminated encephalomyelitis, and post-vaccinal encephalopathy were the most commonly diagnosed adverse events. Furthermore, most of the imaging studies appeared normal. The EEG reports mainly showed background slowing and epileptiform discharges, encephalitis, encephalopathies, and demyelinating disorders. Future studies with larger samples and more vaccine types may help to further unravel the potential neurological effects of COVID-19 vaccinations on recipients.

Neurological Complications Following COVID-19 Vaccination

PURPOSE OF REVIEW

A variety of neurological complications have been reported following the widespread use of the COVID-19 vaccines which may lead to vaccine hesitancy and serve as a major barrier to the public health aim of achieving protective herd immunity by vaccination. In this article, we review the available evidence regarding these neurological adverse events reported, to provide clarity regarding the same so that unfounded fears maybe put to rest.

RECENT FINDINGS

There is a greater than expected occurrence of severe neurological adverse events such as cortical sinus venous thrombosis, Bell's palsy, transverse myelitis, and Guillain-Barré syndromes along with other common effects such as headaches following different kinds of COVID-19 vaccination. Precipitation of new onset demyelinating brain lesions with or without detection of specific antibodies and worsening of pre-existing neurological disorders (like epilepsy, multiple sclerosis) are also a matter of great concern though no conclusive evidence implicating the vaccines is available as of now. The COVID-19 pandemic is far from being over. Till such time that a truly effective anti-viral drug is discovered, or an appropriate therapeutic strategy is developed, COVID-appropriate behavior and highly effective mass vaccination remain the only weapons in our armamentarium to fight this deadly disease. As often occurs with most therapeutic means for the treatment and prevention of any disease, vaccination against COVID-19 has its hazards. These range from the most trivial ones like fever, local pain and myalgias to several potentially serious cardiac and neurological complications. The latter group includes conditions like cerebral venous thrombosis (curiously often with thrombocytopenia), transverse myelitis and acute inflammatory demyelinating polyneuropathy amongst others. Fortunately, the number of reported patients with any of these serious complications is far too low for the total number of people vaccinated. Hence, the current evidence suggests that the benefits of vaccination far outweigh the risk of these events in majority of the patients. As of now, available evidence also does not recommend withholding vaccination in patients with pre-existing neurological disorders like epilepsy and MS, though adenoviral vaccines should be avoided in those with history of thrombotic events.

Should patients with epilepsy be vaccinated against coronavirus disease 2019? A systematic review and meta-analysis

OBJECTIVE

The coronavirus disease 2019 (COVID-19) vaccination coverage, willingness, and safety profiles in patients with epilepsy remain poorly understood. We aimed to summarize the available evidence of COVID-19 vaccination coverage, willingness, and safety profiles among patients with epilepsy.

METHODS

We performed a literature search in the Pubmed, EMBASE, and Cochrane Central Register database between 1 January 2020 and 30 April 2022. We included eligible studies that provided information on the COVID-19 vaccination coverage, willingness, and safety profiles among patients with epilepsy. We investigated the association between baseline characteristics of patients with epilepsy and unvaccination status using a fixed-effect model. We calculated the pooled overall willingness to be vaccinated against COVID-19. We systematically reviewed the safety profiles after COVID-19 vaccination in patients with epilepsy.

RESULTS

Ten eligible observational studies and two case reports yielded 2589 participants with epilepsy or their caregivers. Among 2145 participants that provided the information of vaccination status, 1508 (70.3%) patients with epilepsy were not administered COVID-19 vaccine, and 58% (95%CI 40-75%) of respondents were willing to be vaccinated against COVID-19. Seizure status (active versus inactive, OR 1.84 95%CI 1.41-2.39, I² = 0%) rather than seizure type (focal versus non-focal, OR 1.22 95%CI 0.94-1.58, I² = 0%) was associated with COVID-19 unvaccination status. Vaccines were well-tolerated; epilepsy-related problems such as increase in seizure frequency and status epilepticus after COVID-19 vaccination were uncommon.

CONCLUSIONS

Our findings suggest a low COVID-19 vaccination coverage and willingness in patients with epilepsy. Vaccination against COVID-19 appears to be well-tolerated and safe in patients with epilepsy, supporting a positive outlook toward vaccination in this population.

Seizures following COVID-19 vaccination in Mexico: a nationwide observational study

The COVID‐19 pandemic led to the development and emergency approval of an array of effective vaccines against SARS‐CoV‐2. Given the relatively small number of patients included in vaccine trials, postapproval epidemiological surveillance is crucial to detect infrequent vaccine‐related adverse events. We conducted a nationwide retrospective descriptive study evaluating the incidence of seizures among recipients of SARS‐CoV‐2 vaccines in Mexico from December 24, 2020 (date of administration of first doses nationwide) to October 29, 2021. Among 81 916 351 doses of any vaccine that were administered, we documented seizures in 53 patients, of which 31 (60%) were new onset seizures. The incidence rate of seizures per million doses was highest for mRNA‐1273 (Moderna) with 2.73 per million, followed by BNT162b2 (Pfizer‐BioNTech) with 1.02 per million, and Ad5‐nCoV (CanSino) with 1.01 per million. Thus, we found that seizures following SARS‐CoV‐2 vaccination are exceedingly rare events.

Clozapine and COVID-19 Vaccination: Effects on blood levels and leukocytes. An observational cohort study

OBJECTIVE

To investigate the safety of COVID-19 vaccination in patients on clozapine as regards plasma clozapine concentration and haematological parameters.

METHODS

We conducted a multicentre observational cohort study from 22 February 2021 to 2 September 2021. Primary outcomes were clinically relevant increase in clozapine blood levels (>100 μg/L increase compared to baseline) and clozapine alert levels (>1000 μg/L). Secondary outcomes were granulocytopenia, leukocytopenia and lymphocytopenia. Outcomes were measured approximately 5 days after the first and (where applicable) second dose of COVID-19 vaccine.

RESULTS

This study included 139 patients. Compared to baseline, clozapine blood levels increased significantly (ES = 0.28, p = 0.003) after the second vaccination. Clinically relevant increases in clozapine blood levels occurred in 20/92 patients (22%) and in 16/56 patients (29%) during the first and second phases, respectively. Clozapine alert levels developed in one patient (1%) following the first dose and in three patients (5%) after the second dose. In both phases, changes in white blood cells (WBC) were limited to mild granulocytopenia (3% and 5%), moderate granulocytopenia (1% and 0%) and leukocytopenia (2% and 3%) without cause for extra monitoring according to the guideline.

CONCLUSION

In general, as regards WBC counts COVID-19 vaccination seems to be safe in patients with SMI. Changes in WBC had no clinical implications. Psychoeducation on the symptoms of clozapine intoxication is recommended, especially in patients with clozapine blood levels approaching the upper limit of the therapeutic range. Increase in the C-reactive protein (CRP) level can signal inflammation rapidly and help to prevent clozapine intoxication following vaccination.