In a triumph of science, the first two large-scale trials to report the effectiveness of vaccines against SARS-CoV-2—the deadly, highly contagious virus that causes COVID-19—were both great successes right out of the gate. In November, the pharmaceutical giant Pfizer and the much younger biotech company Moderna both reported that their vaccines were about 95 percent effective in preventing cases of COVID-19. The news came just 10 months after the virus was first isolated and sequenced in a lab in China.