vaccine may be better than one. But doubling the number of jabs each person needs could complicate efforts to immunize billions of people.The latest results from front-runners in the sprint to come up with a vaccine, including the University of Oxford-AstraZeneca Plc partnership and Moderna Inc., highlight that prospect.
Both efforts are conducting final-stage testing with two doses.Producing vaccines and deploying them to the world’s population in the midst of a pandemic would be a massive challenge even if researchers are able to deliver one-dose inoculations.
A need for two would make manufacturing and logistics even more complex.Those challenges would get even tougher if -- as some experts think is possible -- a vaccine’s efficacy wanes.