The UK approved Pfizer and BioNTech's COVID-19 vaccine, the first Western nation to give it the green light

• The UK health regulator on Wednesday approved a COVID-19 vaccine made by the US pharmaceutical giant Pfizer and the German biotech BioNTech.
• The approval makes the UK the first Western nation to approve one of the several vaccines in the late stages of development around the world.
• The UK government said the vaccine would be made available next week.
• Pfizer and BioNTech started developing the experimental shot in March. Vaccine research usually takes several years.

The UK has become the first Western country to officially have a new coronavirus vaccine, the government announced Wednesday.

The country's drug regulator, the Medicines and Healthcare products Regulatory Agency, gave its approval to the vaccine developed by the US drugmaker Pfizer and the small German firm BioNTech.

In a press release, the government said the vaccine would be available within a week.

It said the decision to approve the vaccine followed "months of rigorous clinical trials and a thorough analysis of the data by experts at the MHRA who have concluded that the vaccine has met its strict standards of safety, quality, and effectiveness."

The UK has ordered about 40 million doses, enough for 20 million people to be vaccinated with the two-dose shot. Officials have said healthcare workers will get first priority.

Matt Hancock, the UK health secretary, said on Twitter on Wednesday that the country's National Health Service "stands ready to start vaccinating early next week."

The approval means the UK drug regulator believes that Pfizer's vaccine protects against COVID-19 — the disease caused by the novel coronavirus — and is safe. It came after the agency reviewed all the vaccine's data including from a large, late-stage clinical trial of 43,661 volunteers.

Pfizer submitted the data to health regulators on November 23, after announcing earlier in the month that preliminary results indicated its vaccine was highly effective.

The turnaround from the MHRA has been unusually quick, with regulators in other countries — including the US Food and Drug Administration, the European Medicines Agency, and authorities in Canada, Japan, and Australia — still scrutinizing the data.

Pfizer's vaccine is based on "messenger RNA" technology that uses genetic material to stimulate the immune system to protect against coronavirus infection.

The regulatory approval in the UK marks a milestone for Pfizer and BioNTech but also for other drugmakers, like Moderna, that use the new mRNA technology too. It signals that similar vaccines could work safely and effectively.

Read more: How the pharma giant Pfizer teamed up with a little-known biotech to develop an effective coronavirus vaccine in record time

Pfizer and BioNTech plan to deliver 50 million doses of their vaccine across the world by the end of 2020, with production ramping up to produce more than 1 billion doses in 2021.

The supply chains to get the vaccine to those who need it are already in place in the UK, authorities said. They include designated hubs that can store the vaccine, which requires ultralow temperatures for shipping. It can then can be stored for up to five days in a normal vaccine fridge.

Read more: Drugmakers behind 3 coronavirus vaccines say they work. Here's everything we know about the race for a vaccine and when you might be able to get a shot.

The approval is significant, but it's just the start. To end the pandemic, an estimated 80% of the global population vaccine must be immunized.

"Finding a vaccine is not going to end the pandemic overnight, but we are hopeful of being one step closer to defeating this terrible virus," the UK business secretary, Alok Sharma, said in a statement earlier in the approval process.

The vaccine is given as two shots, three weeks apart, and experts have already raised concerns about people returning for the second shot, especially if they get side effects.

Scientists are also in the unusual position of learning about a disease at the same time as they're creating vaccines against it. They're still investigating how long the vaccine's protection lasts and whether additional shots will be required. It's also unclear whether it stops people from spreading the virus to others.

Above all, we don't know how well Pfizer's vaccine will work in real life. Tracking its use in millions of people, however, is the only way to figure this out. And there's the added benefit that this knowledge could be applied to other harmful diseases.

"Pretty soon the question 'Why only COVID?' will come," Albert Bourla, Pfizer's CEO, said at a Goldman Sachs healthcare conference. "If we prove that you can make vaccines in less than a year, OK, why can't we do that with other medicines, with cancer medicines?"

Read more: Pfizer's top scientist tells us the pharma giant is already thinking about a new version of its coronavirus vaccine for 2021 that can overcome one of its biggest limitations