The coronavirus vaccine will have only a "marginal impact" over the next three months, the four UK chief medical officers have warned the NHS.
The Pfizer/BioNTech jab, approved on Wednesday, will only begin to make a significant dent in hospital admissions and deaths by the spring, they said, also warning that the five-day easing of Covid restrictions over Christmas would increase pressure on hospitals.
Their letter to NHS staff came amid growing concern that the UK may have to wait weeks before a second batch of vaccine arrives, and that it would go no further than 50 vaccine hub hospitals, despite care home residents having top priority.
However, Pfizer and the Department of Social Care insisted on Friday that a second shipment of "millions" more jabs would arrive before January following the delivery of 800,000 doses in the first.
Pfizer vaccine roll-out
Meanwhile a Government source told The Telegraph that the vaccine will be deployed in care homes before Christmas. NHS contractors are to begin training how to unpack the boxes of nearly 1,000 doses and repackage them into smaller batches imminently, the source said, conceding that Scotland was likely to deploy the jab to care homes a few days before England.
It comes amid confusion as to what level of "packing down" is sanctioned by the emergency licence granted by the Medicines and Healthcare products Regulatory Agency.
In their open letter to the healthcare professions, the chief medical officers of England, Scotland, Wales and Northern Ireland, said: "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.
"We think it likely that by spring the effects of vaccination will begin to be felt in reducing Covid admissions, attendances and deaths significantly, but there are many weeks before we get to that stage. We must support one another as a profession as we go to the next, hard months.”
On Tuesday, NHS and social care staff in Wales will begin receiving the jab, the first vaccine dose in Northern Ireland is due to be administered and the first vaccinations will take place in Scotland.
Chris Hopson, the chief executive of NHS Providers, has said vaccinations are ready to begin in England from Tuesday, with NHS England saying a list of hospital hubs providing the jab will be issued over the weekend.
Where the vaccines will be distributed to
It came as Professor Anthony Harnden, the deputy chairman of the joint committee on vaccines and immunisation, which sets the priority list for vaccination, told BBC Radio 4’s World At One that although elderly care home residents should be targeted first, he "understands they might not end up being the first priority group for operational reasons".
The Government source said officials were "trying to get the MHRA to sign off" on plans to distribute the vaccine to care homes, adding: "The people who work for NHS England are being trained to unpack it in a cold room between two and eight C, label the batches up and get them to care homes within 12 hours."
An MHRA spokesman said: "Regulatory approvals required to proceed with the splitting up of packs have been put in place. We are working with NHS and their assemblers to help support them to implement the processes and training they need to have in place to meet our conditions."
A spokesman for Pfizer said: "Pfizer and BioNTech’s plans for the roll-out of the vaccine have not changed since it was shared externally in November that we would supply up to 50 million doses globally in 2020.
"We have delivered the first 800,000 doses to the UK and we expect to deliver millions more this year. Any speculation regarding a change in this plan is incorrect."