Washington, Jan 16 : In a letter to outgoing US President Donald Trump, the country's Health and Human Services Secretary (HHS) Alex Azar has announced his departure on January 20, the inauguration day of President-elect Joe Biden. Azar's letter dated January 12 and made public on Friday came after another Trump administration official, Acting Secretary of Homeland Security Chad Wolf resigned on January 11 in the wake of the January 6 storming of the Capitol building. Wolf was the third cabinet member to step down, following Transportation Secretary Elaine Chao and Education Secretary Betsy DeVos. In his letter, Azar lays out what he considered to be the best accomplishments of HHS over the past four years and adds that controlling the raging Covid-19 pandemic was "by far, the biggest development of Trump's presidency". "While we mourn every lost life, our early, aggressive and comprehensive efforts saved hundreds of thousands or even millions of American lives. "Operation Warp Speed achieved in nine months what many doubted would be possible in a year and a half or more. "As of this date we have two safe and effective vaccines being administered to millions of Americans, with more vaccines likely to be authorised shortly," he says in the letter. Operation Warp Speed repeatedly promised 20 million Americans would have been vaccinated by the end of December 2020, CNN reported. As of Friday, 10.6 million people had been vaccinated. Also referring to the January 6 Capitol violence, Azar said in the letter: "Unfortunately, the actions and rhetoric following the election, especially during this past week, threaten to tarnish these and other historic legacies of this Administration. "The attacks on the Capitol were an assault on our democracy and on the tradition of peaceful transitions of power that the United States of America first brought to the world. "I implore you to continue to condemn unequivocally any form of violence, to demand that no one attempt to disrupt the inaugural activities in Washington or elsewhere, and to continue to support unreservedly the peaceful and orderly transition of power on January 20, 2021." Confirming his departure in a tweet early Friday morning, he said: "I handed in my letter this week along with every other political appointee, effective January 20 at noon. "I believe it is my duty to help ensure a smooth transition to President-elect Biden's team during the pandemic and will remain as Secretary through January 20." Azar was sworn in as the 24th Secretary of Health and Human Services on January 25, 2018. /IANS