Oxford and AstraZeneca's COVID-19 vaccine has been authorized for emergency use in the UK

• The UK has authorized emergency use of the coronavirus vaccine developed by AstraZeneca and the University of Oxford.
• The country has ordered 100 million doses, enough for 50 million people.
• The vaccine can be stored in a standard refrigerator.

Following months of testing, a coronavirus vaccine created by AstraZeneca and the University of Oxford has been authorized for emergency use by the UK.

The vaccine was designed early in the pandemic, and trials on it began in April. It's the second COVID-19 vaccine, after Pfizer BioNTech's, to be authorized in the UK.

The vaccine was approved under Regulation 174 of the Human Medicine Regulations 2012, which allows for the rapid approval of treatments for public-health crises.

The UK has ordered 100 million doses - enough for 50 million people - and, according to AstraZeneca, doses should become available early in the new year.

The vaccine is a viral-vector vaccine and can be stored in a standard refrigerator, unlike other vaccines that require cold storage.

A Department of Health and Social Care representative told the BBC that priority would be to "give as many people in at-risk groups their first dose, rather than providing the required two doses in as short a time as possible."

Recipients must receive a follow-up booster dose within 12 weeks of receiving their first shot of the vaccine.

AstraZeneca's vaccine development has been beset with problems. In September, trials of the vaccine were put on hold after a trial participant in the UK developed an unexplained illness. And in November, the company faced criticism after it was revealed there was a dosing error during late-stage trials for the vaccine, prompting it to combine efficacy rates from groups on two different dosing regimens to announce a 70% efficacy rate in its initial press release announcing trial results.

A group of test subjects in an under-55 test group had erroneously received a smaller dose of the vaccine than another group whose participants received a larger dose. It was found that the smaller dose of the vaccine actually showed more efficacy than the larger dose, at a rate of 90% to 62%.

Scientists, including Moncef Slaoui, the head of the US's vaccine initiative Operation Warp Speed, expressed concerns over a potential misrepresentation of the vaccine's effectiveness, particularly because the vaccine outperformed in the lower-risk under-55 age group.

The dose error and comparatively low efficacy relative to other vaccines caused AstraZeneca's stock to dip in late November.

Still, efficacy of 62% was still above the level health experts generally said would be acceptable for a coronavirus vaccine.

So far, more than 600,000 people across the UK have been vaccinated with the previously authorized vaccine developed by Pfizer and BioNTech.

The UK has struggled in recent weeks following the identification of a new, fast-spreading coronavirus strain. On Tuesday, the country reported a single-day high of 53,125 new cases. The number most likely reflected lags in reporting from Christmas but continued an upward trend throughout December.