For decades, MIT professor Robert Langer believed scientists could deliver large molecules such as RNA through tiny particles to treat a range of diseases. When he told a group of senior scientists about his ideas for drug delivery at a Chinese restaurant in 1979, one of them blew cigar smoke in his face.

“You better start looking for another job,” the scientist said.

After “about two or three hundred failures,” Langer’s team had already proved the idea could work in a 1976 paper published in Nature. Still, he faced a string of rejected grants and skepticism. His research on drug delivery, which led him to co-found Moderna in 2010, went on to prove critical in developing the company’s Covid-19 vaccine. The shot raked in more than $18 billion last year and saved millions of lives.