Dr Andrea Ammon, the head of the European Centre for Disease Prevention and Control (ECDC), said it is “very likely” that Delta will circulate “extensively” across the continent throughout summer – particularly among younger individuals who have yet to be vaccinated.
"This could cause a risk for the more vulnerable individuals to be infected and experience severe illness and death if they are not fully vaccinated,” she said.
Delta has already spread to become the UK’s most dominant variant, having driven a sharp surge in cases that forced government officials to delay the full reopening of society by one month.
The latest data from Public Health England (PHE) show that the number of Delta infections in the UK has risen by 33,630 since last week to a total of 75,953 – a 79 per cent increase. Analysis also shows that 99 per cent of sequenced and genotyped cases across the country are the Delta variant.
In Europe, the variant is beginning to appear in clusters across a number of major countries.
It has accounted for 70 per cent of sequenced cases in Portugal’s greater Lisbon region this month, up from around 10 per cent in May, according to the Portuguese health ministry. In Italy and Belgium, it has made up 20 per cent and 16 per cent of cases respectively.
In France, outbreaks have meanwhile been detected in the southern suburbs of Paris and the Landes region, near the Spanish border.
According to ECDC modelling, there is likely to be a wave of infections, deaths and hospitalisation similar to that experienced last autumn if vaccinations aren’t accelerated and restrictions are eased.
The organisation’s latest published data suggests that 33.9 per cent of adults in the EU/EEA are fully vaccinated, and 57.1 per cent have had at least a single dose.
“There are still too many individuals at risk of severe Covid-19 infection whom we need to protect as soon as possible,” Dr Ammon said.
“Until most of the vulnerable individuals are protected, we need to keep the circulation of the Delta virus low by strictly adhering to public health measures, which worked for controlling the impact of other variants.”
Dr Ammon said two doses of Europe’s approved vaccines provided “high protection against this variant and its consequences. However, about 30 per cent of individuals older than 80 years and about 40 per cent of individuals older than 60 years have not yet received a full vaccination course in the European Union.”
She added: “The Delta variant is more transmissible than other circulating variants and we estimate that by the end of August it will represent 90 per cent of all Sars-CoV-2 viruses circulating in the European Union.
“Unfortunately, preliminary data shows that it can also infect individuals that have received only one dose of the currently available vaccines.
“It is very important to progress with the vaccine rollout at a very high pace. At this stage it becomes crucial that the second vaccination dose is administered within the minimum authorised interval from the first dose, to speed up the rate at which vulnerable individuals become protected.”