London: A major London hospital trust has been told to be ready to receive the first batches of the COVID-19 vaccine being trialled by Oxford University and AstraZeneca by early next month, according to a UK media report on Monday.

The Sun newspaper claims that the country's state-funded National Health Service (NHS) is preparing for an initial rollout of the vaccine from the week commencing November 2.

The vaccine is still in testing, but a major effort has been ordered to have the world-leading hospital in London ready to go as soon as it is given the green light, the newspaper reports.

The report claims that all other clinical trials at the unnamed famous hospital in the UK capital have been paused as all resources go toward preparing to vaccinate thousands of doctors, nurses and other frontline staff with the Oxford/AstraZeneca vaccine as soon as it is ready.

The NHS has a tried and tested track record for delivering vaccination programmes and will work with existing partners across the healthcare system to ensure a COVID-19 vaccine can be deployed safely and effectively, a Department of Health and Social Care statement said, without confirming or denying the latest reports.

A COVID-19 vaccine will only be deployed once it has been proven to be safe and effective through robust clinical trials and approved for use by the independent regulator, it said.

Last week, it had emerged that an independent analysis of the Oxford vaccine trials had found that it was doing everything expected, raising hopes for its ability to combat the deadly virus.

The vaccine, ChAdOx1 nCoV-19 and also known as AZD1222, is considered among the most advanced in the worldwide hunt for a viable vaccine against the novel coronavirus.

The Oxford vaccine is made by taking a common cold virus (adenovirus) from chimpanzees and deleting about 20 per cent of the virus' instructions.

This means it is impossible for the vaccine to replicate or cause disease in humans, but it can still be produced in the laboratory under special conditions. By removing these genetic instructions there is space to add the instructions for the spike protein from SARS-CoV-2.

Once inside a human cell, the genetic instructions for the spike protein need to be 'photocopied' many times a process known as transcription.

In any vaccine system, it is these so-called photocopies that are directly used to make large amounts of the spike protein.

Once the spike protein is made, the immune system will react to it and this pre-trains the immune system to identify a real COVID-19 infection.

So, when the person vaccinated is confronted with the SARS-CoV-2 virus their immune system is pre-trained and ready to attack it.

Oxford University says that adenoviruses have been used for many years to make vaccines, and these are always tested to very high standards to make sure every batch of vaccine has the correct copy of genetic instructions embedded in the vaccine.