Universities may need to cap the number of students they can accept due to the coronavirus crisis, it has been suggested.
"Radical action" will be needed on university admissions for the "foreseeable future", according to a blog co-authored by Sir Chris Husbands, vice-chancellor of Sheffield Hallam University.
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The blog warns that the pandemic presents "serious risks and challenges" for universities and financial stability.
Universities are currently dealing with the knock-on effect of schools and colleges closing, and the cancellation of exams.
The impact of coronavirus on universities
In addition, there are concerns about the impact the worldwide outbreak of Covid-19 could have on international students. The UK is a major player in the international student market, attracting tens of thousands of people to its universities every year.
In his paper, published by the Higher Education Policy Institute (HEPI), Sir Chris sets out a series of possible measures that could help to address some of the risks to universities.
Last week, universities were told by the watchdog the Office for Students to stop making unconditional offers to students for the next fortnight, as part of an attempt to tackle confusion caused by the pandemic and uncertainty among students about how they will secure degree places.
The move came amid concerns that institutions were dropping exam requirements in an attempt to encourage students to confirm a university as their first choice.
Sir Chris says that this action from the Office for Students is welcome, but adds: "Radical action is needed on university admissions for the foreseeable future.
"This means suspending the market in admissions, which has been unrestricted since 2015, and, left as it is, will generate serious institutional instability."
Sir Chris, who co-authored the paper with Natalie Day, head of policy and strategy at Sheffield Hallam University, goes on to say that a number controls need to be imposed to ensure that universities have a viable number of first-year students.
"Realistically, given the damage to school students' education and examination preparation, this will not be a one-year exercise," the paper says.
It also says: "The Covid-19 pandemic presents serious risks and challenges for the sector – some of them existential.
"At the most practical level, there are considerations around institutional operations, admissions, retention and progression and student support, particularly for those of disadvantaged backgrounds, that require innovative and agile responses.
"International student recruitment – an essential component for most universities' sustainable operation – may never recover from the body blow of a global pandemic.
"Alongside this, broader institutional and financial instability threatens to weaken institutions that are central to the immediate response, ongoing research efforts, and future economic and social recovery."
Other measures suggested by the authors include rent support for students and schemes around the retention and progression of students.