NATURE | Antibiotics present an enduring economic puzzle. These drugs changed the world. Yet despite their unique power, the free market doesn’t value them. In just the past two years, four companies that survived the decade-long process of development and testing to get a new antibiotic approved – Achaogen, Aradigm, Melinta Therapeutics and Tetraphase – declared bankruptcy or put themselves up for sale. The reasons are complex. Science writer Maryn McKenna looks at one company, Paratek Pharmaceuticals, and how it has managed to deliver a new antibiotic to the market and survive. COVID-19 has highlighted more than ever the critical need for new antibiotics, and for the need to be better prepared to address public health emergencies. But have we learned that lesson?