Thousands of new coronavirus infections could be spread by university students going home for Christmas, a study by Cardiff University shows.
More than one million UK university students potentially travelling home for the Christmas holidays.
And with some possibly not knowing they have asymptomatic Covid, researchers say this could cause 9,400 new secondary household cases across the entire country at a “modest” estimate.
Returning students may lead to further infections if they interact with individuals outside of their household.
Mass testing of so many students before they leave for home, as suggested by the Welsh Government in collaboration with universities, “will be hugely challenging”, the paper adds.
Universities themselves have also said they cannot test all their students in the timescale needed.
“With the potential movement of over 1 million UK students for the Christmas vacation, even at a modest 1% infection level (meaning 10 in 1,000 students are infected, perhaps many of them without symptoms at the time of travel) that would equate to 9,400 new secondary household cases across the entire country.”
For Wales alone researchers calculate there are 99,900 households with at least one student in higher education here, meaning up to 4,700 secondary infections if 5% of those students are infected.
“We do not readily have access to data on how many of these students live at home versus those who live away and will return home for the holidays.
“But, with 99,900 students, if 1.5% are infected we might expect around 1,400 new secondary infections from students returning home in Wales alone. If 5% are infected we could expect 4,700 new secondary infections.”
The modelling was carried out by Thomas Woolley, senior lecturer in applied mathematics, Joshua Moore, PhD candidate in applied mathematics and Paul Harper, Professor of operational research and Director of the Data Innovation Research Institute at Cardiff University. It was published in The Conversation, the online independent platform for academics to share their work publicly.
“We recently carried out a study to estimate how many secondary infections may be created by students returning home,” the paper said.
“We found that every infected student is likely to pass on the virus to an average of roughly one other person in their household unless precautions are taken – which, in the UK, is likely to mean thousands of new infections, depending on how many students have the virus.
The research, which is yet to be peer reviewed and published in an academic journal, has been handed to the Welsh Government and was also used to inform policy in relation to the two-week firebreak lockdown in Wales when students were asked to remain at their university accommodation, rather than return home.
The data has also been given to the governments in UK, Scotland and Northern Ireland, so it can help inform the wider development of policy, the authors said.
The basis of the researchers’ mathematical model estimates four variables:
- The percentage of students infected with the virus
- The probability of an infected student transmitting the infection to another member of their household
- The estimated the number of occupants in a household, other than the student themselves and;
- The total number of students returning home from campus.
Using local data, including Cardiff University’s in-house, voluntary, asymptomatic testing service, the study also looked at different variables of infections to reach their estimate of around one person in every household being infected.
“If 1.5% of students are infected (15 in every 1,000), we get a range of values for secondary cases, with the most probable being 15 infections,” the study said.
“When 5% of students are infected (50 in every 1,000) the most probably outcome is 50 secondary infections. The results support the idea of each infected student generating roughly one more infection.”
The paper added that 52.9% of all student households in Wales contain at least one other person with a diagnosed long-term illness and “Such people are at greater risk of hospitalisation and death from Covid-19.”
The authors stressed things can be done to reduce the risk, such as mass testing before students travel, although they warns there is a tight time-frame to do this in.
Education Minister Kirsty Williams has already announced plans for students to travel home at Christmas. She has asked students to have a Covid test and leave time for self isolating, if necessary, before leaving university early to go home.
Universities have also been asked to put all teaching online from December 8, although some have said they cannot test all students and face to face learning will have to continue for some, including those on placements and international students. For them term will end as originally planned on December 18.
“Multiple strategies can be adopted to help reduce the number of students taking Covid-19 home,” the researchers added.
“This includes strongly advising students not to mix in the days leading up to departure, implementing staggered departure times and facilitating mass testing of students before they head home.
“Broadly, these are indeed the types of policies that the devolved UK nations have adopted, although mass testing of so many students during such a small window of departure will be hugely challenging.”