Almost all new cases of the coronavirus in the UK are the Delta variant of the virus, a strain first identified in India and a worrying health official in the US, where it has been called a ‘variant of concern’.

Data from Public Health England shows that the Delta variant accounts for 99% of COVID-19 tests sequenced in the UK At least 33,630 cases of the variant were identified last week, bringing the UK total to at least 75,953 cases of the Delta strain.

The data also shows that there is an increased risk of hospitalization with the Delta variant.

As of June 14, PHE reports a total of 806 people hospitalized with the variant, an increase of 423 since last week.

Despite its severity, PHE said two doses of a COVID-19 vaccine offer more than 90% protection against hospitalization. Of those hospitalized with the variant, 527 people were not vaccinated and only 84 of the 806 people had received both doses of a COVID-19 vaccine.

While PHE claims the case fatality rate is low for the Delta variant, it acknowledges that it is “too early to judge Delta’s lethality” against the previously dominant UK strain called Alpha, or other mutations in the virus.

Dr Jenny Harries, chief executive of the UK Health Security Agency, said Delta cases “are increasing rapidly across the country” and “the Delta variant is now dominant”.

“The increase is primarily in younger age groups, a large portion of whom were not vaccinated but are now being asked to receive the vaccine,” Harries said. “It is encouraging that hospitalizations and deaths are not increasing at the same rate, but we will continue to monitor it closely. The immunization schedule and the care we all take to follow the guidelines continue to save lives. “

She urged those who receive COVID-19 vaccines to “make sure you show up for both doses.”

In the United States, the Centers for Disease Control and Prevention upgraded Delta variant to a “worrying variant” earlier this week due to its increased transmissibility. New research suggests the variant nearly doubles the risk of hospitalization compared to the previously dominant strain in the UK

However, the study also found that two doses of the Pfizer-BioNTech or AstraZeneca vaccine offered protection against the Delta strain.

The World Health Organization is also concerned about the variant. WHO chief scientist Dr Soumya Swaminathan told a press conference that the strain was set to become the dominant mutation across the world due to its “dramatically increased transmissibility”.

WHO officials report that 80 countries have reported cases of the Delta variant, which the organization identified as a variant of concern in early May.