Scientists say a new coronavirus variant, which originated in Spain and now accounts for most UK cases, was brought over when people were able to travel again.
A study in Switzerland shows new strain, 20A.EU1, appeared in Spain during the summer and has since spread to multiple European countries.
The variant appeared in the UK in the middle of July when quarantine-free travel to Spain was allowed.
The study has not yet been peer-reviewed, but Dr Emma Hodcroft, an evolutionary geneticist at the University of Basel and lead author of the study, told BBC Radio 4’s Today programme the increase in holiday travel allowed the virus to move across Europe and spread successfully.
She added: "We actually think that it’s really behaviour here that was the key point, and a few failures in the travel system over the summer that we really hope that we can learn from in the future so that next time, when we start opening up travel again, we won’t have to risk having cases rise again."
She identified three failures: the fact that people were still allowed to travel to Spain despite rising cases; lack of screening at airports and the likelihood that people didn’t follow quarantine rules."
