The first doses of the Oxford University and AstraZeneca vaccine are set to be administered in what has been described as a “pivotal moment” in the UK’s fight against coronavirus by the Health Secretary.

Just over half a million doses of the newly approved vaccine will be available from Monday, with vulnerable groups already identified as the priority for immunisation.

Jabs will be delivered at some 730 vaccination sites already established across the UK, with others opening this week to take the total to more than 1,000, according to the Department of Health and Social Care (DHSC).

The vaccine will be administered at a small number of hospitals in England for the first few days, including at Oxford University Hospitals NHS Foundation Trust, where it was developed.

Five other hospital trusts – two in London, and others in Sussex, Lancashire and Warwickshire – will also start delivering the vaccine on Monday.

The bulk of supplies will then be sent to hundreds of GP-led services and care homes later in the week for wider rollout, according to DHSC.

Health Secretary Matt Hancock said: “This is a pivotal moment in our fight against this awful virus and I hope it provides renewed hope to everybody that the end of this pandemic is in sight.”

He urged everyone to continue to follow the coronavirus restrictions while the vaccination programme is under way to “keep cases down and protect our loved ones”.

The UK has secured 100 million doses of the Oxford/AstraZeneca vaccine as part of its contract, enough for most of the population.

While some 530,000 doses are to be available from Monday, DHSC said that tens of millions more are to be delivered in the coming weeks and months once batches have been quality checked.

It comes almost a month after rollout of the vaccine developed by Pfizer and BioNTech began, with more than one million people having now received their first dose.

Second doses of either vaccine will now take place within 12 weeks rather than the 21 days that was initially planned with the Pfizer/BioNTech jab, following a change in guidance which aims to accelerate immunisation.

This has been defended by the UK’s four chief medical officers following criticism, including from the British Medical Association (BMA).

The doctors’ union said it was “grossly and patently unfair” for at-risk patients whose imminent second jab appointments would now be rescheduled.

The Oxford/AstraZeneca jab is easier to transport and store than the Pfizer/BioNTech vaccine, which needs cold storage of around minus 70C.

Because it can be stored at fridge temperatures, between two and eight degrees, it is easier to distribute to care homes and other locations across the UK.

In line with recommendations of the Joint Committee on Vaccination and Immunisation (JCVI), vaccination is being rolled out to priority groups including care home residents and staff, people over 80 and healthcare workers.

GPs and local vaccination services have been asked to ensure every care home resident in their local area is vaccinated by the end of January, according to DHSC.