[3] Due to the ongoing COVID-19 pandemic, the new organisation was not formally established until 1 April 2021,[3] by which time it was called the UK Health Security Agency.

During questioning by the Science and Technology Committee of the House of Commons, Harding said she held the interim leadership while a full application process was carried out.

[8][5] Over time, UKHSA has built a relationship with Korea Disease Control and Prevention Agency, signing a memorandum of understanding and various visits between the two organisations.

[9][10] The Telegraph first leaked news of the plans for the new agency on 16 August 2020, writing that Public Health England was to be "scrapped" and replaced by a single body combining it with NHS Test and Trace, in response to the COVID-19 pandemic.

[11] A leaked memo to staff written by the head of Public Health England, Duncan Selbie, said that the aim of the new body was to boost expertise with "much needed new investment".

[15] The Institute for Government said that the UKHSA faced financial uncertainty and big cuts in its first year, frustrating recruitment, even at board level.

[26][27][28] The Guardian quoted allies of hers who, in response, said that she had quickly learned after being appointed chair of NHS Improvement in 2017 and that she had a record of "getting things done" while working in business.