The Covid-19 vaccine will "definitely" be ready to go into care homes in the next two weeks, BBC reports.
The Medicines and Healthcare products Regulatory Agency (MHRA) said it had approved the way doses would be distributed to homes.
It means care home residents and staff may not be the first to receive jabs, despite being the top priority.
But the UK's chief medical officers say the vaccine will only have a "marginal impact" on winter hospital numbers.
In a letter to colleagues, the chief medical officers of England (Prof Chris Whitty), Scotland (Dr. Gregor Smith), Wales (Dr. Frank Atherton) and Northern Ireland (Dr. Michael McBride) warn this winter could be "especially hard" for the health service due to coronavirus.
"Although the very welcome news about vaccines means that we can look forward to 2021 with greater optimism, vaccine deployment will have only a marginal impact in reducing numbers coming into the health service with Covid over the next three months," they said.
