Three more countries have been added to the UK quarantine list.
Croatia, Austria and Trinidad and Tobago have followed Spain and France onto the 'unsafe' list.
Anyone returning from the countries will have to self-isolate for 14 days.
The restrictions come into force at 4am on Saturday.
Transport secretary Grant Shapps also announced travellers returning from Portugal to the UK will no longer have to self-isolate for two weeks.
Mr Shapps chaired a meeting on Wednesday to discuss the impact of rising cases and announced the news on Thursday afternoon.
The Foreign Office has said it would look at putting any country with more than 20 cases per 100,000 people on its quarantine list.
Croatia's average number of cases has risen to 29.5 cases per 100,000 people in the past week - compared to a rate of 13.54 per 100,000 a week ago.
And cases on the Caribbean islands of Trinidad and Tobago have more than doubled in a week.
Austria's rate has nearly doubled in the past week, with 20.31 cases per 100,000 in the past seven days, up from 10.45 cases per 100,000 the week before.
Other areas reportedly of concern include Greece, Denmark and Switzerland.
