Trips to countries on the continent accounted for 85.9% of imported Covid cases, of which 51.2% had visited Greece (21.0%), Croatia (16.3%,) or Spain (14.0%).
The research sought to assess the the impact of travel corridors on Covid transmission.
Travel restrictions were first eased on 3 July 2020 when the UK government introduced 'travel corridors' or 'air bridges' which allowed holidaymakers to take a trip to designated countries without having to quarantine.
Visitors from Spain, Greece and Croatia, as well as other countries, were permitted into England and the rest of the UK without having to quarantine on the original travel corridor list.
Spain was removed from the list of safe countries to travel to after fears were raised that the country was experiencing a second wave of coronavirus infections on July 26.
"A total of 4,207 SARS-CoV-2 positive importation cases were analysed, along with 18,856 contacts, of which 888 sequenced genomes were available for comparison to all UK genomic data (131,387 sequences from the UK and in the COG-UK dataset by 5 December 2020)," the report said.Before the introduction of travel corridors, just 2.9% of travel-related cases were recorded, the report by Public Health England (PHE) and the Covid-19 Genomics UK Consortium said.The research showed the greatest number of imported cases were found in Greater London (28.6%).
Most cases from Greece were brought in the end of August and continued into September. The scientists believe this may be due to a younger age demographic.
"No travel restrictions were imposed on Greece during this time period and it was the source of greatest imported SARS-CoV-2 cases during this study period," the report said.
Those aged 16-20 were responsible for greatest number of travel-related cases and onwards contacts.
"This identifies an opportunity to direct public health awareness campaigns to younger travellers, with the intention to promote behaviours that will reduce the risk of SARS-CoV-2 acquisition and enhance compliance with quarantine on return to the UK," the paper said.
The paper said the data "highlights the need for active surveillance of imported cases of SARS-CoV-2 for the introduction of travel corridors in a timely manner".
This study looked at contact-tracing data from NHS Test and Trace and genomic data made available through the COVID-19 Genomics UK (COG-UK) consortium, which receives samples from NHS hospital diagnostic labs and mass community testing labs.
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