Nearly three-quarters of coronavirus cases among University of Cambridge students last autumn have been traced back to a single nightclub, highlighting the risks of reopening venues in the next phase of the UK government’s roadmap.
Students who attended socially distanced events during freshers’ week and over Halloween were the source of the biggest infection cluster at the university, according to researchers who analysed the effectiveness of Cambridge’s coronavirus screening programme, which tested 10,000 students weekly at its peak and was the largest in the UK.
Genomic sequencing showed that the virus spread rapidly among students who mixed between households and courses on nights out. Cases fell dramatically once the second lockdown was announced, as students complied with the rules and socialised within households of six to 20. Further outbreaks were curtailed by the expansion of a PCR testing programme, which the university estimates reduced the rate of transmission by a third.
Nicholas Matheson, the researcher at the Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID) who designed the screening programme, said the findings could prove instructive for the next phase of the government’s reopening plans, under which nightclubs could reopen on 21 June.
“The demographics of the people who might attend nightclubs are also in general terms people who’re not yet vaccinated,” he said. “Our data is definitely supportive of a role for coronavirus testing in helping to control infections – but we don’t think it’s a magic bullet, it should be part of a package of measures.”
Dinesh Aggarwal, a researcher at Cambridge’s medical school, said venues could work in collaboration with researchers to use genomic sequencing to establish how they could open in safer ways, for instance using ventilation or different forms of social distancing, as well as which activities could be hosted safely.
Cambridge could also serve as a template for other universities, which struggled to contain mass outbreaks on campus at the beginning of the autumn term last year. Young people aged 18-22 are at the end of the vaccine queue, meaning it is uncertain whether most students will have been double-vaccinated before starting university in September.
Matheson advocated that universities take a pragmatic approach to allowing students to socialise, striking a balance between allowing mass events with widespread mixing to go ahead and confining students to small households. “An alternative is to provide facilities for socialising in a way we think may be overall less risky,” he said.
Matheson said that although universities were planning for a number of different scenarios depending on vaccination levels, the situation with new variants and national infection rates, testing would definitely feature across campuses during the next academic year.
“The most favourable end of the spectrum may see a limited role for testing, that might involve PCR testing a fraction of students on a regular basis for surveillance purposes. Less favourable scenarios would require surge testing or regular screening,” he said.
The Cambridge researchers found most transmission took place within halls of residence and among students on the same course, and that spreading to the local community or between staff and students was limited.
Four-fifths of students at Cambridge agreed to swab their noses and throats weekly. Swabs were then pooled in the same sample tube as other students from their household, making the programme cheaper and more efficient. These were then analysed at the Cambridge Covid-19 testing centre in collaboration with AstraZeneca and Charles River Laboratories.
Nearly half (45%) of the 671 students diagnosed with coronavirus during term time were identified or pre-emptively asked to self-isolate due to the screening programme.