The face of the US fight against coronavirus has blamed Donald Trump and divisiveness "from the top down" for the country's poor response to the pandemic, which has left the country with the most cases and deaths.
Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said Covid-19 also exposed weaknesses in the country's health care system, which led to racial disparities in suffering.
Speaking at the World Economic Forum via a video link, he warned that evolving mutations could reduce vaccine effectiveness.
The US has suffered about 25 million cases and more than 400,000 deaths as former president Donald Trump failed to contain the spread of the disease.
"There were a few things that were complicating and overlapping and explain, almost the unimaginable, about how a very, very rich country got hit the worst," he said.
“We had a situation where, instead of concentrating from the top down on the data and science and realising that we must make decisions based on evidence, there was a considerable amount of mixed messaging from the top down.
"That cost us dearly.”
Asked to identify problems in the US response, Dr Fauci said that allowing coronavirus health care to become a political instrument and the lack of federal government involvement at state level had cost the country.
"It makes it extremely problematic to address a public health crisis when you're in the middle of divisiveness in the country," he said.
"When public health issues become politically charged – when wearing a mask is a political statement – you can't imagine how harmful that is to a unified public health message.
“The states were sort of left on their own. We had a disparate, inconsistent response from one state to the other," he said.
“We needed to have good co-operation between the federal government and the individual local states, which we did not have.”
Dr Fauci has continued in his role for President Joe Biden’s administration.
He said the coronavirus found weaknesses in the US, including a lack of access to care and race-based inequalities that allowed the virus to flourish.
“A pandemic sheds a very bright light on a lot of the weaknesses in a society. For us it showed the deficiencies of our healthcare system.
“The other thing it shed a bright, embarrassing light on is the extraordinary disparities we have in health, where in our country a vastly disproportionate amount of suffering among our brown and black people in which the incidence of them getting infected is much higher and their hospitalisation is significantly higher.”
As coronavirus mutates, with variations being identified in England, South Africa and Brazil, he is concerned that one will reduce the effectiveness of vaccines.
Dr Fauci said he is also worried that some people are delaying the second dose of Covid-19 vaccinations.
“The UK variant has … the inherent capability of making you more sick. It does not appear to have a substantial effect on vaccine efficacy.
He said that in the South Africa variant some antibodies were “completely negated in their efficacy” by the mutation and there is “considerable more threat to vaccine efficacy, even though the cushion of vaccine efficacy is currently good enough.
“Having said that, it’s an evolving situation.”