Scientists advising the government have expressed concerns to ministers about an increase in foreign travel this summer.
Latest documents from the Scientific Advisory Group for Emergencies (SAGE) have been released, showing advice given to ministers earlier this month.
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A document from 14 July stressed the importance of global surveillance of the emergence of new variants of COVID-19 and added: “Any increase in foreign travel over the summer and the return of international students to universities in the autumn is of particular concern.”
And in the same document from the Scientific Pandemic Influenza Group on Modelling, Operational sub-group (SPI-M-O), experts warned that September and October “will be a particularly risky point in the trajectory of the pandemic”.
They also said that there could be “significant pressures” if people engage in more normal behaviours at the same time as schools and universities go back.
From Monday, fully vaccinated travellers from most EU countries and the US will not have to quarantine when arriving in England, Scotland and Wales.
Foreign Secretary Dominic Raab has described the new rules as part of a “modest opening up”, which follows on from most COVID restrictions in England being lifted on 19 July.
Latest figures show the UK has reported 29,622 new cases and 68 more coronavirus-related deaths in the latest 24-hour period.
Shapps: More jabs means more travel
The figures compare with 31,117 infections and 85 fatalities announced on Thursday, while 36,389 cases and 64 deaths were reported on this day last week.
The seven-day average for infections is 36.1% down from the previous week, while fatalities are up by 25.1%.
It comes after the UK recently recorded seven consecutive days of falling case numbers.
Boris Johnson said earlier this week that this data was “encouraging” but warned COVID “still presents a significant risk”.
And Sky’s science correspondent Thomas Moore has said part of the UK’s third wave is now “below the radar”, due to “significant numbers” of cases not showing up in the official daily statistics.