An evacuation-style operation will take place to get students home safely for Christmas after England’s lockdown.
The government has told universities to allocate departure dates during a «student travel window» between 3 and 9 December, to minimise the risk of them spreading Covid-19.
Many students will be offered rapid result tests, and teaching must move online from 9 December.
Unions said the plan «leaves little room for error».
Universities Minister Michelle Donelan said the week after the four-week national lockdown in England ends on 2 December was chosen because «students will pose a much reduced risk to their loved ones and their community».
She told BBC Breakfast the timing means that anyone who develops symptoms on 9 December will still «have enough time to isolate and then return home for Christmas».
Students are strongly advised to travel during the travel window.
«This is a choice. If they choose to leave after [9 December] they will run the risk of potentially not getting home to Christmas with that isolation window,» Ms Donelan said.
She described the roll-out of rapid result Covid tests to as many students as possible as a «complementary element» to the travel window.
The distribution is set to begin at the end of November, and universities in areas with higher rates of the disease will be prioritised.
Any student who tests positive for Covid will be required to self-isolate for 10 days under the current guidelines.
‘I couldn’t live with myself if I brought Covid home’
Lily Scourfield, who is studying medicine in Cardiff, said she thinks it is «vital» that she gets a Covid-19 test before going home for Christmas.
Her mum has cancer and is in the «extremely vulnerable» category, meaning she is at high risk.
«I spent some time away from her in the first wave, now I haven’t been able to see her for quite a while,» Lily told BBC Radio 5 Live.
«If I don’t get a test before I go home, I’ll need to isolate in some capacity. I just couldn’t live with myself if I brought anything home.»
Dr Jo Grady, general secretary of the University and College Union, said allowing one week for around one million students to travel «leaves little room for error».
«If the government instead told universities to move online now it would provide much more time to stagger the movement of students and better protect the health of staff, students and their wider communities,» she said.
The Department for Education says universities will now start working with their local public health teams and local transport operators to manage the mass movement in a staggered fashion.
Universities should soon begin contacting students with allocated travel days, and some may hire coaches to help with the transportation.
The department insists there is enough capacity on the nation’s public transport system for this to take place safely, adding that many students will have their own transport or be collected by parents.
Ms Donelan also said she expected Wales and Northern Ireland to publish plans for students’ return in the coming days.
She confirmed that students will not need to have a negative test result before travelling home.
The government wants to «facilitate as much testing as possible», she said, but will target universities in areas with higher infection rates and proportions of vulnerable students.
De Montfort and Durham universities have been running pilot projects for rapid Covid testing, including identifying those who might be infectious but have no symptoms.
The «lateral flow tests» give results in about 20 minutes, without the need for a lab.
Prof Jacqui Ramagge, executive dean of the science faculty at Durham University, said students who receive a positive test result from these then undertake a a PCR (polymerase chain reaction) test – the type you get in NHS centres – to confirm their status.
That is because the PCR tests are «the ones that are legally required,» she added.
She said mass testing of students is «absolutely essential».
«So many people in the age group that our students are in are asymptomatic carriers of the virus, and so if we only test those who are symptomatic, we miss a large number of people,» she said.
Despite universities’ best efforts, many students contracted the virus within days of arriving on campus. An estimated 40,000 students have become infected whilst in their university towns, leading to thousands having to isolate.
This sparked concerns about infected students bringing the virus back home with them, thus accelerating the spread of the disease.
There were suggestions that students might have to remain at university for an extra two-week period, so they could isolate, before returning home.
But this was criticised by the National Union of Students as likely to have a negative effect on student mental health.
Deputy chief medical officer Dr Jenny Harries said: «The mass movement of students across the country at the end of term presents a really significant challenge within the Covid-19 response.»
University lecturers and the NUS had warned of the risks of bringing 1.2 million students back to universities since the summer, and urged ministers to move courses online as the default.
But the government had defended the continued use of face-to-face teaching.
Responding to the new guidance, NUS president Larissa Kennedy said: «The government have finally listened to our calls to ensure students can travel home safely for Christmas.
«We particularly welcome this mass-testing approach as it equips students with the knowledge to make informed decisions about travel ahead of the winter break.»
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