The power of messenger RNA is evident now as vaccines from Moderna, BioNTech, and Pfizer have weakened the power of the coronavirus in accessible and high-uptake communities.

But in early 2020, when a mysterious and dangerous new pathogen spread in Wuhan, China, it was far from a safe bet as a vaccine base that would stop the virus.

When work began, even the decision to convert an entire company to the new virus seemed alarming. But the signs from China were for Moderna CEO Stephane Bancel and BioNTech boss Dr. Ugur Sahin, clear enough that they started spinning their ships, told CNBC in interviews for a documentary about the vaccine race released Friday.

“The night China locked Wuhan, I thought, ‘When was the last time I knew a city was locked down because of an infectious disease?'” Bancel recalled. “And what goes through my head is: What do the Chinese know that we don’t know?”

Bancel said he woke up sweating at 4 a.m. and found, “Jeez, there’s going to be a pandemic like 1918.”

Sahin read a newspaper in the Lancet in late January describing the outbreak in China.

“I did a series of calculations, quick calculations, and found that it was already spreading,” said Sahin. “And it was clear that it was already too late to stop the disease.”

But he was convinced that BioNTech, which at the time mainly focused on personalized cancer therapies, could make a difference. His company reached out to Pfizer and suggested they work on a vaccine against the novel coronavirus using the same technology, messenger RNA, that they had previously worked with to fight the flu.

“We had the first contact a few days after the start of the project,” said Sahin. “Pfizer wasn’t interested at the time.”

Albert Bourla, Pfizer’s CEO, confirmed Sahin’s report, saying that for the first few months of 2020 he was focused on keeping the company’s operations going in China. But by the end of February, he said, he had determined that Pfizer needed to work on a treatment and a vaccine.

“What’s the best approach?” Bourla said he asked his team.

Kathrin Jansen, director of vaccine research and development at Pfizer, said she had assessed all existing technologies, including protein-based vaccines and vaccines with viral vectors.

“They all have too few advantages and too many disadvantages,” she said.

Other companies that entered the race in the early days had taken different approaches: Johnson & Johnson and AstraZeneca, a partnership with Oxford University, focused on virus-vector vaccines, which were also relatively new. Other companies like Sanofi and Novavax relied on more proven technologies in protein-based vaccines.

But messenger RNA was a risk; it had never been used as an approved vaccine or drug before.

“I struggled a bit with the decision,” said Bourla. But after another meeting with the team “they convinced me”.

Then Sahin called a second time. The outbreak was already in New York at the time, he said. When he got to Jansen, he described the work BioNTech was already doing and asked if Pfizer would like to work together.

“And I said: absolutely,” Jansen recalled. “Let’s talk about it.”

At Moderna, it was never a question that messenger RNA would be the way to go; That was the technology that started the company in 2010. However, that didn’t mean there weren’t any questions.

“Even in March there were voices saying vaccines were false hopes,” recalled Dr. Stephen Hoge, President of Moderna. “It felt like we were even having to defend the idea of ​​an attempt for a while.”

“When we thought about how we’re getting into Phase 1, what is it like preparing for a pandemic, the world’s eyes felt like they were looking at Moderna as that biotechnology … ‘What are they trying to do? do? ‘”said Hamilton Bennett, senior director, vaccine access and partnerships at Moderna.

“It was only when we passed over in this March WHO announcement that it was a global pandemic, an emergency, that I think people realized that what we are doing is not sandboxed about our technology to demonstrate, ”said Bennett. “We’re developing a vaccine that will stop the pandemic.”

The companies succeeded in one of the greatest medical races in history. This is where they remember how it happened.