The chase to tame the coronavirus has been a worldwide pursuit this year, gaining intensity and taking on increasing urgency as the deadly pathogen spreads across continents.
In the United States - the worst-hit country in the pandemic with the world's highest infection count and death toll - Dr Moncef Slaoui has been at the helm of helping the nation bring a Covid-19 vaccine to its market in record time.
The retired vaccine developer, who spent nearly three decades at British pharmaceutical giant GlaxoSmithKline researching a vaccine for malaria, took on the role as chief science adviser of America's Operation Warp Speed in May.
The initiative's main aim is to speed up the finding, making and dispensing of a Covid-19 vaccine.
"We couldn't have found anyone better than Moncef," Dr Elias Zerhouni, a former director of the National Institutes of Health, told USA Today.
"If there is one person in my view who has been there, done that, it's Moncef Slaoui."
Moroccan-born Dr Slaoui, 61, has been described as a hands-on leader with a fierce work ethic who never needs much more than four hours of sleep a night.
He has visited about a dozen clinical trial facilities and manufacturing sites to understand the Covid-19 vaccine development process since he assumed the role.
In taking on the job, he had to give up his positions on the boards of US biotech company Moderna and other firms that posed potential conflicts of interest.
He says he has earned just US$1,001 (S$1,334) in the six months since he joined the government service, but insists he is "having a blast" as his teammates are all united in a common mission to make safe, effective vaccines in the shortest possible time.
"Nobody has a different agenda," he said.
In Europe, Oxford University professor Sarah Gilbert is leading the team with British pharmaceutical giant AstraZeneca, developing perhaps the world's cheapest vaccine.
The experimental vaccine - whose efficacy is reported to be as high as 90 per cent - built on research pioneered by Prof Gilbert and others on vaccines based on a virus that causes common colds in chimpanzees.
In the course of her career at Oxford, Prof Gilbert, 58, has set up her own research group to create a vaccine that would work against all strains of flu, led trials of an Ebola vaccine, and worked on developing a vaccine for the Middle East respiratory syndrome.
Friends and peers have described her as a reserved, conscientious person with "true grit", BBC reported last week.
Given the urgency of finding a Covid-19 vaccine, she has been working from very early in the morning until late at night, sometimes sending e-mails at unorthodox hours.
"From the beginning, we're seeing it as a race against the virus, not a race against other vaccine developers," Prof Gilbert said earlier this year.
"We're a university and we're not in this to make money."
In Africa, Harvard-trained geneticist Christian Happi, the director of the African Centre of Excellence for Genomics of Infectious Diseases (Acegid), is at the forefront of coronavirus research on the continent, expected to be the last to gain widespread access to a vaccine.
Acegid, housed in Redeemer's University in south-western Nigeria, was the first laboratory in Africa to sequence the coronavirus genome.
Its researchers have developed a potential DNA-based Covid-19 vaccine specifically for Africa, but they face a struggle for funding, according to Cornell University's Alliance for Science.
Although there have been relatively few Covid-19 infections in Africa than elsewhere - about two million cases against the global total of 65 million - Professor Happi stresses that it is crucial to develop a vaccine intended for people in Africa, given their genetic diversity and the different pathogens circulating in the region.
"Genetically, Africans are different from people in the Global North," he said, explaining that it was one of the reasons previous vaccines for other diseases developed in the West usually fell short when administered to African people.
"If you want to design a vaccine for Africans, primarily you need to start from Africa and understand how they are responding."
The global initiative of the Covax facility must also be credited for its work as the world's first attempt at a multilateral effort to ensure fair and equitable access to Covid-19 vaccines, no matter rich or poor.
Co-led by the World Health Organisation, the Coalition for Epidemic Preparedness Innovations, and Gavi, the Vaccine Alliance, Covax has achieved the feat of pulling together over 170 countries representing nearly two-thirds of the world's population to support its cause.
Members are promised access to the Covid-19 vaccines the facility secures, and in October, it met a significant milestone when about 80 wealthier nations committed to make upfront payments for the vaccines.
"The fact that the world is coming together to try to put together a shared vision and a shared facility itself is historical," Dr Seth Berkley, chief executive of Gavi, the Vaccine Alliance, told news site Vox in October.
"I believe that this is the largest multilateral effort since the Paris climate agreement... That's a positive thing."
