A single shot of either the Oxford-AstraZeneca or the Pfizer-BioNTech Covid jab reduces the chance of needing hospital treatment by more than 80%, an analysis in England shows.
The Public Health England (PHE) data showed the effect kicked in three to four weeks after vaccination. It was based on people aged over 80 who were the first to receive the jab.
Government scientists hailed the result, but stressed that two doses were needed for the best protection.
It comes after similar findings were published by Scottish health authorities last week, which they hailed as "spectacular".
The PHE data, which has not been peer reviewed, also suggested the Pfizer vaccine, which started being rolled out a month before the AstraZeneca vaccine, leads to an 83% reduction in deaths from Covid. This was based on people over the age of 80 who had died.
The data also showed vaccination cuts the risk of people over 70 developing any Covid symptoms by around 60%, three weeks after an initial dose.
Prof Van-Tam, England's deputy chief medical officer, said the decision to give the AstraZeneca vaccine to older people was "clearly vindicated".
Source: BBC News, 1 March 2021