{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,18]],"date-time":"2026-10-18T01:00:09Z","timestamp":1792285209596,"version":"4.4.0"},"reference-count":33,"publisher":"Canadian Science Publishing","issue":"2","license":[{"start":{"date-parts":[[2021,3,1]],"date-time":"2021-03-01T00:00:00Z","timestamp":1614556800000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/www.nrcresearchpress.com\/page\/about\/CorporateTextAndDataMining"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Psychiatry Neurosci"],"published-print":{"date-parts":[[2021,3]]},"abstract":"<jats:sec><jats:title>Background<\/jats:title><jats:p> Monitoring of white cell counts during clozapine treatment leads to cessation of therapy if levels fall below pre-determined 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. <\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p> 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. <\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p> We observed reductions in absolute neutrophil counts ( p = 0.005), lymphocyte counts ( p = 0.003) and white cell counts ( p &lt; 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 &lt; 2.0 \u00d7 10<jats:sup>9<\/jats:sup>\/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. <\/jats:p><\/jats:sec><jats:sec><jats:title>Limitations<\/jats:title><jats:p> This was a retrospective chart review; larger cohorts are required. Clozapine plasma levels were largely not measured by clinicians. <\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p> 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. <\/jats:p><\/jats:sec>","DOI":"10.1503\/jpn.200208","type":"journal-article","created":{"date-parts":[[2021,3,11]],"date-time":"2021-03-11T12:55:42Z","timestamp":1615467342000},"page":"E232-E237","source":"Crossref","is-referenced-by-count":22,"title":["COVID-19 infection causes a reduction in neutrophil counts in patients taking clozapine"],"prefix":"10.1139","volume":"46","author":[{"given":"Siobhan","family":"Gee","sequence":"first","affiliation":[{"name":"From the Pharmacy Department, South London and Maudsley NHS Foundation Trust, Denmark Hill, London, United Kingdom"},{"name":"and the Institute of Pharmaceutical Sciences, King\u2019s 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