New York City's health commissioner, Dr. Oxiris Barbot, resigned Tuesday, expressing her "deep disappointment" with the way New York City Mayor Bill de Blasio has handled the COVID pandemic and his use of the department's expertise.

In her resignation letter, sent to de Blasio and members of the media, Barbot said, "I leave my post today with deep disappointment that during the most critical public health crisis in our lifetime, that the Health Department's incomparable disease control expertise was not used to the degree it could have been."

Earlier this year, the New York Times reported de Blasio initially ignored Barbot's advice about canceling large gatherings and closing businesses. Last month, he stripped control of the city's COVID-19 contact-tracing program from the health department, and placed the program under Health and Hospitals, the agency that runs the city's public hospitals.

Barbot's replacement was announced as Dr. Dave Chokshi-a Rhodes Scholar who served at the Louisiana Department of Health during Hurricane Katrina and was the principal health adviser to the Secretary of Veterans Affairs in the Obama administration.

At his Tuesday news conference, de Blasio thanked Barbot for her service and the important work she did during the crisis. He told reporters it became clear it was time to move forward and "create a new approach" for how to handle the pandemic.

Earlier this year, New York City was the epicenter of the pandemic in the United States, with daily deaths passing 400 per day. But this past month, the city saw the lowest number of hospitalizations since the pandemic began.