A worrying spike of coronavirus infections in Europe is being driven by the delta variant, according to global health leaders, even as immunization rates in some countries are on the way up.
Increased cases reported in the U.K. and Portugal have forced officials to reimplement lockdown restrictions or hold off on lifting pandemic mandates. Officials in France, Germany and Spain said they are closely monitoring clusters of infection tied to the delta variant.
The strain, also known as B.1.617.2, was first detected in India. It is now "well on its way to becoming the dominant variant globally because of its increased transmissibility," Soumya Swaminathan, the World Health Organization's chief scientist, said Friday.
Pfizer-BioNTech and Moderna vaccines have been shown to be effective against this strain.
A recent study from Public Health England showed two doses of the Pfizer-BioNTech vaccine were 88% effective against symptomatic disease from the delta variant compared with 93% effectiveness against the alpha variant, the variant first detected in the United Kingdom. The vaccine only provided 33% protection after just one dose.
Still, in the U.S., the Centers for Disease Control and Preventions shared similar concerns of the spread of the delta strain. The CDC declared last week that it was a "variant of concern," meaning it poses a significant threat to unvaccinated people.
U.K. Prime Minister Boris Johnson announced last week a delay in plans to lift the final elements of the nation's lockdown restrictions, citing "a faster than predicted" spread of the strain.
Originally set to end Monday, Johnson said restrictions on businesses and large events will remain in place until July 19.
In the U.K., data shows 99% of sequenced and genotyped confirmed coronavirus cases across the country are the delta variant, according to Public Health England.
The government's weekly data as of June 18 showed numbers of the delta variant in the U.K. have risen by 33,630 from the previous week to a total of 75,953.
This comes despite the nation's high immunization rate, with 59.5% of the adult population fully vaccinated from the coronavirus. A reported 81.6% of the adult population have received one dose, according to government data.
Dr. Jenny Harries, chief executive of U.K. Health Security Agency, said in a statement, "The increase is primarily in younger age groups, a large proportion of which were unvaccinated but are now being invited to receive the vaccine."
On Friday, the government announced every adult over the age of 18 is eligible to receive a coronavirus vaccine.
Authorities in Portugal banned all weekend travel in and out of Lisbon, the capital, to cut down on any further spread of the virus to other parts of the country.
Portugal's National Health Institute reported this weekend the delta variant is shown to be in at least 60% of new cases in Lisbon. The country reported more than 1,000 new COVID-19 cases for the fourth day in a row on Saturday, according to Reuters.
Cases tied to the delta strain are reported as being low in France, Spain and Germany, but each nation's health minister warn that the delta variant is perceived as a real threat.
As of June 14, Spain reported the delta variant accounted for less than 1% of cases.
Spain's Catalonia region, in the northeast, reported 20% of new cases were linked to the delta strain, the region's health official, Josep Maria Argimon, announced at a press conference Thursday.
Argimon warned that delta could be the predominant variant throughout the country in two to four weeks.
That hasn't stopped the nation from moving forward with lifting some COVID-19 restrictions. Spanish Prime Minister Pedro Sánchez announced Friday that masks would no longer have to be worn outdoors in the country, starting June 26.
German Health Minister Jens Spahn said it's not if the delta variant becomes dominant, but "when and under what conditions."
France reported that 2% to 4% of virus samples being analyzed in the country showed the delta variant, according to French Health Minister Olivier Véran.
"We are in the process of crushing the virus and crushing the pandemic, and we must in no way let the Delta variant get the upper hand," Véran said last week, according to The Financial Times.
"You might say this is still low but it is similar to the situation in the UK a few weeks ago," he said.