You may be surprised to learn that of the trio of long-awaited coronavirus vaccines, the most promising, Moderna’s mRNA-1273, which reported a 94.5 percent efficacy rate on November 16, had been designed by January 13. This was just two days after the genetic sequence had been made public in an act of scientific and humanitarian generosity that resulted in China’s Yong-Zhen Zhang’s being temporarily forced out of his lab. In Massachusetts, the Moderna vaccine design took all of one weekend. It was completed before China had even acknowledged that the disease could be transmitted from human to human, more than a week before the first confirmed coronavirus case in the United States. By the time the first American death was announced a month later, the vaccine had already been manufactured and shipped to the National Institutes of Health for the beginning of its Phase I clinical trial. This is — as the country and the world are rightly celebrating — the fastest timeline of development in the history of vaccines. It also means that for the entire span of the pandemic in this country, which has already killed more than 250,000 Americans, we had the tools we needed to prevent it. … For measles, for scarlet fever, for tuberculosis, for typhoid, the miracle drugs didn’t bring rampant disease to a sudden end — they shut the door for good on outbreaks that had largely died out already. This phenomenon is called the McKeown hypothesis — that medical interventions tend to play only a small role compared to public-health measures, socioeconomic advances, and the natural dynamics of the disease as it spreads through a population. The new coronavirus vaccines have arrived at what counts as warp speed, but not in time to prevent what CDC director Robert Redfield predicts will be “the most difficult time in the public-health history of this nation.” —David Wallace-Wells