The United Kingdom(UK) has approved the Oxford-AstraZeneca COVID-19 vaccine.
The vaccine is the second to be approved by the UK Medicines and Healthcare products Regulatory Agency (MHRA).
It is said to be between 62 percent and 90 percent effective against the virus.
The first doses are due to be given on Monday amid rising coronavirus cases.
The UK has ordered 100 million doses, enough to vaccinate 50 million people.
This would cover the entire population when combined with the full order of the Pfizer-BioNTech jab, according to Health Secretary, Matt Hancock.
Vaccination centres will now start inviting patients to come and get the jab from next week.
Priority groups for immunisation have already been identified, starting with care home residents, the over-80s, and health and care workers.
Eventually, all over 50s and younger adults with health conditions will be offered a jab in the first phase of rollout – more than 25 million people in total.
The MHRA has authorised two full doses of the Oxford vaccine, with the second dose to be given four to 12 weeks after the first.
The immunisation campaign will now shift to giving as many people as possible their first dose of vaccine with a second dose following within that period.
When the Pfizer-BioNTech jab rollout began, the aim was to give the second dose after three weeks.
But based on advice from the Joint Committee on Vaccination and Immunisation, the aim now is to give as many vulnerable people some protection from COVID-19, irrespective of the jab they are given.
The vaccine was developed by scientists at Oxford University.
So far, the UK has recorded over 2,000,000 cases of COVID-19 and over 71,000 fatalities.
A new strain of the infection which is said to be 70 times more contagious has been discovered in the country.