Data from the rollout of AstraZeneca's Covid-19 vaccine shows one dose of the shot results in 80 per cent less risk of death from the infection, according to a Public Health England study released on Monday.

It also said protection against death from the Pfizer-BioNTech, vaccine rises from approximately 80 per cent after one dose to 97 per cent after two doses in its latest analysis.

PHE said this was the first study on protection against mortality from the AstraZeneca vaccine based on data from a real world setting.

The study looked at new symptomatic cases of Covid-19 between December and April and examined the vaccination status of people who died within 28 days of their positive test for the disease.

People who had a single dose of AstraZeneca vaccine were 55 per cent protected against death, with a figure of 44 per cent protection for a single dose of Pfizer, compared to unvaccinated people.

"Combined with the protection vaccines offer against becoming a case in the first place, this is equivalent to approximately 80 per cent protection against death in individuals vaccinated with a single dose of either vaccine," PHE said in a statement.

Protection against mortality from the Pfizer-BioNTech vaccine improved to 69 per cent for cases who had their second dose at least a week before they tested positive. Combined with the estimated protection from getting COVID-19 to start with, this is equivalent to an estimated 97 per cent protection, PHE said.

In another dataset, PHE said that it was estimated that two doses of the Pfizer-BioNTech vaccine reduces the risk of hospitalisation by 93 per cent for people over 80 years of age.