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. 2022 Jan 24;37(4):e28.
doi: 10.3346/jkms.2022.37.e28.

An Outbreak of Breakthrough Infections by the SARS-CoV-2 Delta Variant in a Psychiatric Closed Ward

Yu Mi Wi  1 , Si-Ho Kim  1 , Kyong Ran Peck  2
Affiliations

An Outbreak of Breakthrough Infections by the SARS-CoV-2 Delta Variant in a Psychiatric Closed Ward

Yu Mi Wi et al. J Korean Med Sci. .

Abstract

Background: A rapid decline in immunity and low neutralizing activity against the delta variant in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccinees has been observed. This study describes an outbreak of coronavirus disease 2019 (COVID-19) breakthrough infections caused by the SARS-CoV-2 delta variant in a psychiatric closed ward.

Methods: Data from epidemic intelligence service officers were utilized to obtain information regarding demographic, vaccination history, and clinical data along with SARS-CoV-2 PCR test results for a COVID-19 outbreak that occurred in a closed psychiatric ward.

Results: Among the 164 residents, 144 (87.8%) received two doses of vaccines and 137 (95.1%) of them received ChAdOx1 nCoV-19 vaccine. The mean interval between the second vaccination and COVID-19 diagnosis was 132.77 ± 40.68 days. At the time of detection of the index case, SARS-CoV-2 had spread throughout the ward, infecting 162 of 164 residents. The case-fatality ratio was lower than that in the previously reported outbreak before the vaccination (1.2%, 2/162 vs. 6.9%, P = 0.030). Prolonged hospitalization occurred in 17 patients (11.1%) and was less prevalent in the vaccinated group than in the unvaccinated group (8.5% vs. 25.0%, P = 0.040).

Conclusion: The findings of this study highlight that while vaccination can reduce mortality and the duration of hospitalization, it is not sufficient to prevent an outbreak of the SARS-CoV-2 delta variant in the present psychiatric hospital setting.

Keywords: Breakthrough; COVID-19; Psychiatric Hospital; SARS-CoV-2 Delta Variant.

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Conflict of interest statement

The authors have no potential conflicts of interest to disclose.

Figures

Fig. 1
Fig. 1. An epidemic curve of the COVID-19 patients in a psychiatric hospital. The solid arrows indicate routine testing of PCR, while the empty arrows indicate testing in symptomatic patients. The horizontal axis indicated the date on which the test was performed, while the vertical axis is the number of confirmed patients.
COVID-19 = coronavirus disease 2019.
Fig. 2
Fig. 2. Outcomes according to the period from vaccination to COVID-19 diagnosis. The horizontal axis is the period from vaccination to diagnosis of COVID-19, while the vertical axis is the number of vaccinated residents (Total number = 164).
COVID-19 = coronavirus disease 2019.
See this image and copyright information in PMC

References

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