In the coronavirus pandemic, the United States enjoyed remarkable good fortune with the mRNA vaccines, developed in less than a year, demonstrating 90 percent or more efficacy in clinical trials and manufactured in hundreds of millions of doses. We still don’t understand how Americans can look askance at this lifesaving gift. Consider, by contrast, that the malaria vaccine took decades to reach this point, and its efficacy is far lower, in some cases 36 percent among children 5 to 17 months old. But the pilot program in the three African nations demonstrated “strong community demand” for the vaccine, according to the WHO, and it can be delivered through existing child immunization programs.