In a concrete hangar in Aguadilla, Puerto Rico,
Katrina Mayes is working with precision and purpose. Wisps of smoke surround her, wafting off the dry ice she is using to jerry-rig a cardboard vaccine carrier. Her task: to create a vapor phase vent to moderate the temperature of the cooling container from around minus 80 degrees Celsius (for storing Pfizer’s COVID-19 vials) to minus 15 degrees Celsius (to accommodate supplies of the Moderna vaccine).
At 29, the biochemist and virologist has spent much of her professional life indoors, where the U.S. government has entrusted her to handle some of the world’s most lethal pathogens—including Ebola, Lassa fever, and Nipah viruses—at top-secret Biosafety Level Four facilities. “I shower six times a day,” she tells me. “I’m the cleanest person you’ll ever meet.” Her winning smile and gallows humor mask the gravity of her work, which has involved diffusing poison-laced letters that have been mailed to federal buildings.