Britain yesterday became the first Western country to approve a Covid-19 vaccine for general use, giving the green light to the Pfizer/BioNTech drug.
As authorities in the US and Europe probe other candidates, here is how countries have sped up their approval procedures to face up to the pandemic.
Britain was able to approve the Pfizer vaccine after the independent Medicines and Healthcare products Regulatory Agency (MHRA) gave its all-clear.
The MHRA used a "rolling review" process from June to assess the vaccine in record time.
Teams of scientists had worked "around the clock" on different aspects of the safety assessment, often tackling several topics in parallel, MHRA chief June Raine said.