The Rockefeller Institute, whose investigators were intimately involved in the problem, alone included extraordinary people. By 1912 its head Simon Flexner -his brother wrote the "Flexner report" that revolutionized American medical education -used immune serum to bring the mortality rate for meningococcal meningitis down from over 80% to 18%; by contrast, in the 1990s at Massachusetts General Hospital a study found a 25% mortality rate for bacterial meningitis. Peyton Rous won the Nobel Prize in 1966 for work he did at the institute in 1911; he was that far ahead of the scientific consensus. By 1918 Oswald Avery and others at Rockefeller Institute had already produced both an effective curative serum and a vaccine for the most common pneumococcal pneumonias. At least partly because of the pandemic, Avery would spend the rest of his career studying pneumonia. That work led directly to his discovery of the "transforming principle"his discovery that DNA carries the genetic code.