SACRAMENTO (CBS13) — Officials are investigating the coronavirus-related death of a vaccinated inmate who was hospitalized last week.

According to Sacramento County, its health services department was notified of the 76-year-old inmate’s death Monday morning. The inmate reportedly was already being treated for long-term significant and underlying health conditions before testing positive for COVID-19 on October 25.

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He was admitted to the hospital for low oxygen levels prior to the positive test. The county did not say where the inmate was being housed but said the housing unit was quarantined and contact-tracing efforts were underway.

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“We are working closely with Correctional Health staff to conduct contact tracing and mitigate the spread,” said county Public Health Officer Olivia Kasirye. “Quarantine protocols are in place and extensive testing is being done.”

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The 76-year-old had been vaccinated in June. His identity has not yet been released.