Igor Shepherd, a Wyoming Department of Health planning manager, said he doubts the "so-called pandemic" is real and believes that vaccine development programmes are attempts by Russia and China to spread the socialist ideology around the world.
Mr Shepherd made the comments at a 'Keep Colorado Free and Open' event last month but they only came to light on Friday, as the US reported a daily record of 229,077 new coronavirus infections, according to New York Times data.
US health officials recorded 2,637 Covid-19 deaths nationwide on 4 December, bringing the total to almost 280,000 – the highest number of any country in the world and 103,044 more than second-placed Brazil, Johns Hopkins University figures show.
Covid-19-related hospitalisations are also at record levels, pushing many medical centres and emergency service operations to breaking point.
Mr Shepherd was introduced at the event as being a Wyoming Department of Health employee in the over hour-long presentation in Loveland, Colorado, on 10 November.
His baseless and unsubstantiated comments are likely to fuel vaccine scepticism in a state where 15 people have died from the disease since 1 December.
Wyoming Health department director, Mike Ceballos, and state health officer, Dr Alexia Harrist, did not respond to requests for comment, including on when they became aware of Mr Shepherd’s talk and what, if anything, they have done in response.
Phone and social media messages left for Mr Shepherd on Friday by AP were not returned.
Mr Shepherd has worked for the health department since 2013 and has been a part of the state’s team responding to Covid-19, though not in a leadership role, department spokeswoman Kim Deti said.
“All of the things we’ve said for months and the thousands of hours of dedicated work from our staff and our local partners on this response effort and our excitement for the hope the vaccine offers make our overall department position on the pandemic clear,” Ms Deti added.
Despite rising infections, hospitalisations and deaths, millions of people across the US are concerned about the safety of vaccines.
Some 42 per cent of America's population (around 137 million) said they would not get a jab when one is ready, according to a Gallup survey published last month, although that figure was down from 50 per cent in September.
Former presidents Barack Obama, George W. Bush and Bill Clinton have all said they may get vaccinated publicly in a bid to boost confidence.
Researchers have worried for months that politicised scepticism of coronavirus vaccines could slow the country's recovery from the pandemic. Vaccines are more effective if most of the population is inoculated.
“If poorly designed and executed, a Covid-19 vaccination campaign in the US could undermine the increasingly tenuous belief in vaccines and the public health authorities that recommend them — especially among people most at risk of Covid-19 impacts,” the researchers wrote.
Additional reporting by Associated Press