ArticleJournal of psychiatry & neuroscience : JPN2021
COVID-19 infection causes a reduction in neutrophil counts in patients taking clozapine.
Article in Journal of psychiatry & neuroscience : JPN, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 17 papers, 3 of them syntheses that pooled it.
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The trial behind it
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Who cites it
17 citing papers in PubMed, 3 syntheses or guidelines pooled it, 24 citations in OpenAlex.
- Risk factors associated with blood dyscrasia during clozapine treatment: a systematic review and meta-analysis.Psychological medicine · 2026Pooled it
- Clozapine Therapy and COVID-19: A Systematic Review of the Prevalence Rates, Health Outcomes, Hematological Markers, and Patient Perspectives.Schizophrenia bulletin · 2023Pooled it
- Clozapine prescribing barriers in the management of treatment-resistant schizophrenia: A systematic review.Medicine · 2021Pooled it
- A study on the effect of COVID-19 infection on the serum concentration of antipsychotic drugs.BMC psychiatry · 2025Article
- COVID-19 disease outcomes in patients receiving clozapine versus other antipsychotics: a national study in Qatar.Frontiers in psychiatry · 2025Article
- Decoding Clozapine-Induced Agranulocytosis: Unraveling Interactions and Mitigation Strategies.Pharmacy (Basel, Switzerland) · 2024Article
- Can lithium be used in the setting of clozapine commencement in patients with COVID-19 associated neutropenia: A case report.Clinical case reports · 2024Article
- COVID-19 Vaccines and the Virus: Impact on Drug Metabolism and Pharmacokinetics.Drug metabolism and disposition: the biological fate of chemicals · 2023Review
- Clozapine Serum Concentrations Are Disrupted by SARS-CoV-2 Vaccinations.Case reports in psychiatry · 2023Article
- Clozapine and Neutropenia in Patients with Schizophrenia and SARS-CoV-2 Infection.Neuropsychiatric disease and treatment · 2022Article
- Neutropenia after the coadministration of clozapine and nirmatrelvir-ritonavir in a patient with SARS-CoV-2 infection: A case report with a literature review.Frontiers in psychiatry · 2022Article
- Reduction in Absolute Neutrophil Counts in Patient on Clozapine Infected with COVID-19.International journal of environmental research and public health · 2021Review
- Clozapine-related immunodeficiency: Implications for Parkinson's disease psychosis in the context of the COVID-19 pandemic.Revue neurologique · 2021Article
- Transient drop in the neutrophil count during COVID-19 regardless of clozapine treatment in patients with mental illness.Revista de psiquiatria y salud mental · 2021Article
- A Decrease of Neutrophils After COVID-19 Vaccination in a Treatment-Resistant Patient With Schizophrenia Taking Clozapine.Journal of clinical psychopharmacologyArticle
- Exploring the Impact of COVID-19 Vaccination on Patients Taking Clozapine.Innovations in clinical neuroscienceArticle
- Transient drop in the neutrophil count during COVID-19 regardless of clozapine treatment in patients with mental illness.Revista de psiquiatria y salud mentalArticle
Corrections and comments
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Authors and funding
2 authors at 2 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Background: Monitoring of white cell counts during clozapine treatment leads to cessation of therapy if levels fall below predetermined values. Reductions in white cell counts, driven by lower levels of lymphocytes, have been observed with coronavirus disease 2019 (COVID-19). Neutropenia during COVID-19 has not been reported. We present data for 56 patients who were taking clozapine and had COVID-19. Methods: We included patients who were taking clozapine at the time they tested positive for COVID-19. We compared absolute neutrophil counts, lymphocyte counts and white cell counts between baseline and the first week of infection, and baseline and the second week of infection. Results: We observed reductions in absolute neutrophil counts (p = 0.005), lymphocyte counts (p = 0.003) and white cell counts (p < 0.001) between baseline and the first 7 days of COVID-19. All cell counts had returned to baseline levels by days 8 to 14. Six patients experienced neutropenia (absolute neutrophil counts < 2.0 × 109/L) and of those, 4 underwent mandatory cessation of clozapine. For 3 patients, clozapine treatment had been established for more than 6 months with no previous neutropenia, neutrophil levels returned to baseline within 2 weeks and no further neutropenia was observed on restarting treatment. Limitations: This was a retrospective chart review; larger cohorts are required. Clozapine plasma levels were largely not measured by clinicians. Conclusion: These data strongly suggest that mild neutropenia in the acute phase of COVID-19 in patients who are well established on clozapine is more likely to be a consequence of the virus than of clozapine treatment.
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