(BCN) -- San Francisco's public health director, who oversaw the city's responses to the COVID-19 pandemic and fentanyl crisis, announced his resignation on Thursday. Dr. Grant Colfax is stepping down after spending nearly six years as the city's leading health official. The San Francisco Department of Public Health did not provide a reason for his resignation. Deputy Director of Health Dr. Naveena Bobba will become the acting director after Colfax's last day on Feb. 7. "As Director of Health, Dr. Colfax contributed to saving lives of San Franciscans during one of our city's most challenging times," said newly inaugurated Mayor Daniel Lurie in a press release. "His leadership has enabled to our recovery, and I thank him for his service to our city." Dr. Grant Colfax, San Francisco Department of Public Health Colfax started serving as the director just before the COVID-19 pandemic began. Through his leadership, San Francisco saw some of the lowest death rates in the country for a major city. "Dr. Colfax led SFDPH as it implemented one of the most intensive and comprehensive responses in the country that kept San Francisco's death rate to half the state rate and one-third the U.S. rate," health department officials wrote in the press release. Colfax was also tasked with tackling the emergence of fentanyl, a highly potent synthetic opioid that has killed more people in San Francisco than COVID-19 since 2020. Preliminary data from the city's Medical Examiner's Office revealed that 589 people died in 2024 due to accidental drug overdose, with the majority of them caused by fentanyl poisoning. That was a decrease from 2023, when the city experienced its deadliest year for overdoses with 806 accidental deaths. How a San Francisco program helped a new mom turn around her life The drop in overdose deaths has been attributed in part to Colfax leading the implementation of substance use treatment programs, including providing emergency shelter and medication for those seeking treatment for addiction. "In the past 12 months substance use residential treatment admissions have increased 35% and the median wait time for a bed has decreased by 50%," the department said in the release. "Methadone starts and buprenorphine prescriptions are up 39% and 52% respectively in 2024 compared with 2023." Colfax also helped initiate preventative measures and treatment for HIV/AIDS in San Francisco during his tenure. In a 13-month span, more than 55,000 people were vaccinated for monkeypox. The city also saw the lowest rate of HIV infections ever in 2023. "We have accomplished much in the past six years," Colfax said in the release. "There is no doubt that the dedicated, hard working and compassionate staff at DPH will continue to deliver for San Francisco." Copyright © 2025 Bay City News, Inc.