The US is now advising citizens not to travel to Australia "due to Covid-19-related travel restrictions".
Australia, as well as 21 other countries, were added to the Level 4 travel advisory list on Tuesday.
The Level 4 travel warning is the "highest advisory level due to greater likelihood of life-threatening risks" according to the US Department of State.
In the warning about Australia, The Centers for Disease Control and Prevention said "avoid travel to Australia. If you must travel to Australia, make sure you are fully vaccinated before travel."
"Because of the current situation in Australia, even fully vaccinated travellers may be at risk for getting and spreading COVID-19 variants," the CDC warning said.
The announcement has been made as Australia has started recording one of the highest Covid-19 rates per population, sitting just behind France.
However, as far as case numbers and mortality rate goes, the risk is far higher for those travelling in the other direction.
Australia has recorded 110 Covid-19-related deaths per million people according to Our World in Data. The US has recorded 2,565 per million people.
As of January 18, the case fatality rate is 0.14 per cent in Australia and 1.26 per cent in the US.
Currently, the US is on Australia's 'yellow' list, which recommends people "exercise a high degree of caution" when travelling. They are not currently required to reconsider the need to travel or not travel; the two higher ratings.
The news follows hot on the heels of Queensland removing quarantine for international travel. From Saturday January 22, fully-vaccinated international arrivals will be allowed to skip the 14-day quarantine after delivering a negative Covid test within 24 hours of arrival.
Along with Australia, the CDC has also placed Argentina, Israel, Egypt and Qatar on the Level 4 list.
Canada and many parts of Europe, Africa, South America are also under the same advisory.