Australia’s health officials have said they are on high alert after cases of highly transmissible new variants of the coronavirus, discovered in Britain and South Africa, have made it into the country.

Given the new variants, the government cut the number of travelers from overseas and required negative Covid-19 tests from those boarding planes and more testing at local quarantine facilities.

“So long as people are travelling, the risk of the virus seeping into the community is already there,” New South Wales Premier Gladys Berejiklian said, according to Reuters.

“Anything we can do to reduce that risk is really important, especially now when we understand what these strains are doing, and all the experts advise in due course that these mutated strains will become the dominant strain.”