Study data published in the British Journal of Psychiatry suggest that clozapine treatment may increase the risk for coronavirus disease (COVID-19). Compared with patients taking other antipsychotic medications, those taking clozapine were found to be at substantially elevated risk for COVID-19, even after adjusting for other known COVID-19 risk factors. These results may have important implications for patients receiving antipsychotics for schizophrenia-spectrum disorder.

This retrospective cohort study extracted clinical records data from a large mental healthcare provider in the United Kingdom. Patients with a clinical diagnosis of a schizophrenia-spectrum disorder who were taking antipsychotic medications between 2019 and 2020 were eligible for inclusion. The primary outcome was infection with COVID-19 between March 1, 2002, and May 18, 2020. COVID-19 infection was determined from medical records data, including clinician-entered diagnoses, pathology results, and hospital admission records.

Cox proportional hazard models were used to compute the risk for COVID-19 in patients taking clozapine compared with to that in patients taking other antipsychotics. Models were adjusted for smoking status, gender, race/ethnicity, body mass index (BMI), and number of days spent in inpatient care for COVID-19.

The study cohort comprised 6309 patients with schizophrenia-spectrum disorder who were receiving any type of antipsychotic medication. Mean age was 46.5 ± 14.8 years, 61.7% were men, 33.2% were White, 50.6% were Black, and 13.7% were Asian or of another ethnicity; 2.5% were missing data on ethnicity. Over the follow-up period, 102 patients (1.62%) tested positive for COVID-19. In crude models, patients taking clozapine were significantly more likely to test positive for COVID-19 than patients not taking clozapine (hazard ratio [HR], 2.62; 95% CI, 1.73-3.96). This association remained significant after adjusting for age, gender, ethnicity, smoking status, inpatient status, and BMI (HR, 1.76; 95% CI, 1.14-2.72).

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These results are consistent with prior research suggesting that clozapine may increase the risk for pneumonia and other infections. Concerning study limitations, the investigators noted that models were not adjusted for certain comorbid conditions, such as hypertension or respiratory and metabolic diseases. Further research with more complete patient data is necessary to expound on these findings.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry.

Please see the original reference for a full list of authors’ disclosures.


Govind R, Fonseca de Freitas D, Pritchard M, Hayes RD, MacCabe JH. Clozapine treatment and risk of COVID-19 infection: retrospective cohort study. Br J Psychiatry. Published online July 27, 2020. doi:10.1192/bjp.2020.151