Two doses of the Oxford/AstraZeneca Covid-19 vaccine gives an estimated 94 percent protection against death from the disease in people over 65, Public Health England said on Thursday in a weekly surveillance report of real-world data.

PHE said the majority of the data was derived from a period when the Alpha variant, first detected in England, was still dominant and did not provide a specific estimate of protection from death that the vaccine offered against the now more widespread Delta variant, first detected in India.

PHE also said that for the under 40s, early estimates suggested a single dose of Pfizer's vaccine is 61% effective against symptomatic disease and a single dose of the Moderna vaccine is 72% effective.

"This data gives us even more confidence that the vaccines offer high levels of protection against Covid-19 across all age groups," said Jamie Lopez Bernal, consultant epidemiologist at PHE.