LONDON, June 18 (Xinhua) -- The Delta variant first identified in India now accounts for almost all of Britain's coronavirus cases, Public Health England (PHE) said Friday.
Some 33,630 cases of the variant were recorded in the last week, according to the PHE. The Delta variant is thought to be 65 percent more transmissible in households than the Alpha variant, which was previously dominant in Britain's cases.
The increase in Delta cases is largely among younger age groups, many of whom are unvaccinated or have only just received their first dose, said the PHE.
Jenny Harries, chief executive of the UK Health Security Agency, said it was "encouraging" that hospital admissions and deaths are not rising at the same rate as cases, but experts will "continue to monitor it closely".
Britain reported another 11,007 coronavirus cases in the 24-hour period, bringing the total number of coronavirus cases in the country to 4,600,623, according to official figures released Thursday.
British Prime Minister Boris Johnson announced Monday a four-week delay to the final step of England's roadmap out of COVID-19 restrictions until July 19, amid a surge in cases of the Delta variant.
New data published this week by the PHE showed the AstraZeneca vaccine is 92 percent effective against hospitalization from the Delta variant after two doses, and the Pfizer vaccine is 96 percent effective against hospitalisation after two doses.
Experts have warned that coronavirus may continue to evolve for years to come, and eventually it is likely current vaccines will fail to protect against transmission, infection, or even against disease caused by newer variants.
To bring life back to normal, countries such as Britain, China, Russia, the United States as well as the European Union have been racing against time to roll out coronavirus vaccines.