Kamala has officially resigned:
(CNN) Vice President-elect Kamala Harris has formally submitted her letter of resignation from the US Senate to California Gov. Gavin Newsom ahead of Inauguration Day.
Read the letter obtained by CNN:
January 18, 2021
Governor Gavin Newsom
1303 10th Street, Suite 1173
Sacramento, CA 95814
Dear Governor Newsom:
I hereby resign as Senator from the State of California, effective January 18th, 2021 at 12:00 p.m. EST. As I assume my duties as Vice President of the United States, I would like to thank the people of California for the honor of serving them in the U.S. Senate over the past four years.
Sincerely,
Kamala D. Harris
United States Senator
https://edition.cnn.com/2021/01/18/politics/harris-resignation-letter-senate/index.html