The situation was dire. As the pandemic raged in March, some Covid-19 patients in Milan were going into septic shock and their blood pressure was perilously low.

A California drug company wanted to ship emergency medication to those patients, but commercial flights to Italy had been drastically scaled back. So it called PCI Pharma Services, a Philadelphia company that specializes in packaging and shipping drugs around the world. It took nearly a week, but PCI secured permits and arranged for courier jets, drivers and trains to deliver the drugs to Milan.

“That day when the drug arrived, six people were saved,” said Salim Haffar, PCI’s chief executive.

As countries prepare to distribute hundreds of millions of Covid-19 vaccines — some of which require storage as cold as the South Pole in winter and meticulous handling — the highly specialized operations of companies like PCI Pharma are in heavy demand. And Wall Street, which likes nothing better than a hot trade with the potential for big profits, is rushing to grab a piece of the action.

Investors were already snapping up shares of vaccine makers like Moderna and Pfizer, whose vaccine, developed with BioNTech, was introduced in the United States on Monday and requires an exceptionally low storage temperature of negative 70 Celsius. FedEx and UPS, whose shares have already risen this year as the pandemic forced millions to rely on online shopping, could benefit further from their roles in vaccine delivery.