After co-chairing the Biden-Harris transition's COVID-19 Advisory Board from November 2020 to January 2021, she was selected by President Joe Biden to serve as Senior Advisor to the White House COVID-19 Response Team and Chair of the Presidential COVID-19 Equity Task Force.

[5] She has also been working with community partners in Puerto Rico and the U.S. Virgin Islands to overcome obstacles in testing, self-isolation, and quarantine.

[6] A paper submitted in May 2020 of which Nunez-Smith was senior co-author considered state-level reporting of race and ethnicity of Covid cases and outcomes in the United States, for data up to April 2020, and found reporting from many states of this dimension to have been weak or lacking—an important omission, the paper argued, as from the data available it estimated that members of Black populations had encountered a 3.6 times greater risk of death, and members of Latin populations a 1.9 times greater risk of death, compared to White populations.

[10][11] Under her direction, the Health Equity Task Force issued a report advising the Biden Administration on how to best support COVID-19 response and recovery efforts in communities hit hardest by the coronavirus pandemic.

[14][15] Since its inception, ECHORN has both expanded research and leadership capacity in the region, and served as an international model for reducing the global burden of non-communicable diseases among structurally marginalized communities.