Pascal Soriot has led the charge to make AstraZeneca one of the first pharmaceutical companies in the world to produce a vaccine against Covid-19.
The development of the vaccine with scientists at Oxford University -- and their decision to make it available at cost -- has made the Anglo-Swedish firm a household name.
Since announcing successful clinical trials and having the vaccine passed by regulators, the company has faced a spate of challenges.
Production and delivery delays of the vaccines in Europe have caused turmoil, while queries over clinical trial data have prompted questions about its effectiveness among the over-65s.
Now, several countries, including France and Germany, have suspended the jab pending an investigation into whether it caused blood clots.
The World Health Organization and the European Medicines Agency have both said the benefits of the vaccine outweigh any risk.
But the attacks have left Soriot, a 61-year-old Frenchman, defending the company on multiple fronts, even as he leads the takeover of US biotech firm Alexion for $39 billion.
With each question or suspension of the jab, AstraZeneca has kept a consistent line: the vaccine is safe and it is cooperating with governments and regulators.
Soriot voiced annoyance with armchair critics in an interview with The Times in December. "I'm a player, I'm not a watcher or a commentator," he said.
He began his career in Australia, took Australian citizenship and still has a home in Sydney with his family.
He revealed he made final preparations for the merger announcement with Alexion from a quarantine hotel.
On a conference call in February at the time of the company's annual results, he vigorously defended the company's work on the life-saving vaccine.
"Has everything been perfect? No," he said, but stressed the vaccine provided 100 percent protection against the most serious cases of Covid-19.
The last 12 months have been his hardest ever, he admitted to The Times, as he shuttled between the United States, Europe and Australia.
His only company often was his cat, Daisy, he added.
- Pharma veteran -
Soriot took over as chief executive of AstraZeneca in 2012 and has been no stranger to battles.
He had locked horns with Pfizer even before the US firm tied up with Germany's BioNTech in the race to develop the first Covid vaccine.
In 2014, Pfizer had tried to takeover AstraZeneca for £69 billion but failed.
Soriot argued that the development of new cancer treatments would suffer -- and lives were at stake -- if the US firm was allowed to do so.
A graduate of the Maison Alfort veterinary school, southeast of Paris, who holds an MBA from the HEC Paris business school, Soriot entered the pharma industry in the 1980s.
In Australia, he spent years in sales for the French laboratory Roussel Uclaf, which was absorbed by the German pharmaceutical group Hoechst to become Hoechst Marion Roussel in 1995.
He became managing director the following year, then moved to Japan in 1997.
Through a series of mergers, the group became part of the giant Sanofi group.
Soriot then joined the Swiss pharmaceutical company Roche in 2006.
Then, from 2009 to 2010, he headed Genentech, a Roche subsidiary since 1990 which was then bought out in full in 2009 after a hostile takeover bid.
He was poached to lead AstraZeneca in 2012.
The markets remain generally confident in the company thanks to promising drugs in development.
The company's stock price has almost doubled in five years.
But it is down 2 percent this year, while the FTSE-100 index, of which AstraZeneca is a member, has risen 5 percent since January 1.
According to analysts, the stock has suffered in recent months from a proposed price for the purchase of Alexion that many consider too high.