Austerity measures left public health services "denuded", the head of the UK's Health Security Agency has said.
Professor Dame Jenny Harries told the COVID-19 inquiry that budget cuts placed local health officials under "significant pressure" - and community infection prevention became a "declining resource".
The former deputy chief medical officer was a regular at the daily Downing Street news conferences during the pandemic.
Asked how funding cuts impacted local authorities' planning and response to emergencies, Dame Jenny said: "I think it is fair to say, and I'm pretty confident it's evidenced, that some of the health protection skills were denuded, particularly from the smaller local authorities where you would perhaps have one director of public health, one consultant and one other - really quite small."
She also said that ring-fenced public health budgets reduced as a result of austerity, adding it was her "understanding" that the poorest areas of England experienced disproportionately high cuts.
Her comments contradict the assertions of former Conservative prime minister David Cameron, and ex-chancellor George Osborne.
Both rejected claims their austerity measures weakened the NHS when they gave evidence to the inquiry last week.
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Module 1 of the inquiry, which is set to run until mid-July, is looking at the UK's preparedness for pandemics in the time before COVID hit.
Dame Jenny, as head of the UKHSA, was asked about the body's predecessor Public Health England, which in turn grew out of the Health Protection Agency.
She called its formation "a painful birth" that "wasn't welcomed by all", and agreed there was some confusion over roles in its emergency preparedness.
Public Health England was established in 2013 as an executive agency of the Department of Health.
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Cameron speaks out at COVID inquiry
'No groupthink'
Asked whether she agreed if its close political relationship with government was a cause for concern among staff, Dame Jenny said: "I recognise the cause of concern and I recognise the perception, I don't necessarily agree with the content."
The scientist was also asked about the potential risk of "groupthink" in PHE advisory groups.
Dame Jenny told the inquiry: "I don't hold with the groupthink agenda. I think people spoke very freely.
"They may not have all thought the same thing and at the end of the meeting you have to come to a consensus statement and position to support progressing whatever topic in charge is."
While she acknowledged "there is a feeling of people being left out of the room", she said not everyone can impose their views in these settings and "there has to be a practical limit to that".
Former health secretary Matt Hancock and ex-Scottish first minister Nicola Sturgeon will give evidence to the inquiry later this week.
