The UK on Wednesday became the first country in the world to give the green light to Pfizer for its COVID-19 vaccine.
It will start to be administered as soon as next week, with priority given to elderly people and medical workers.
The question remains, however, how and why the UK regulator, the Medicines and Healthcare Products Regulatory Agency, moved so fast.
For one thing, countries have different regulations.
At the FDA in the U.S., final approval takes a few weeks to a few months, but the agency only starts reviewing a product once trials are finished.
The UK, however, uses a so-called 'rolling review' process.
"Under the rolling review system, they analyzed and reviewed the data as they come in, not after once the studies are done, so in this way I think the UK was able to make their decision much faster than other countries might have done."
On the other hand, a former director of the KCDC says the UK might have been under some extreme pressure.
"The UK is currently facing a very large number of cases and deaths. It's very serious. They have been in a position where they would love to give vaccines to people as soon as possible. The UK government rushed to get permission, knowing that the U.S. will apply for approval on December 10th."
Other countries are expected to authorize the Pfizer vaccine soon.
The U.S. FDA will start reviewing it next week, while countries in the European Union are waiting for the European Medicines Agency to approve it at the end of this month.
"It's only one country that approved the vaccine right now. Since the UK approved the vaccine already, I think the South Korean government will be able to review Pfizer's vaccine without being under pressure."
European Union officials, however, slammed the UK's decision to approve the Pfizer vaccine, saying the decision was made too fast, and that the UK health authorities should not put speed before safety.
Choi Won-jong, Arirang News.