The surge in coronavirus cases is helping speed up the development of vaccines.

The surge in coronavirus cases is helping speed up the development of vaccines.

Vaccine trial participants in Abu Dhabi, United Arab Emirates, in October. Vaccine developers conduct their trials in parts of the world where the virus is spreading.Credit...ReutersNov. 19, 2020, 7:07 a.m. ETThere is a slender silver lining to the out-of-control pandemic: It is hastening the testing of vaccines that could eventually end it.The surging number of virus cases has already allowed Pfizer and Moderna to accelerate the testing of their vaccines, which appear to be very effective at preventing Covid-19, and it is likely to speed the evaluations of promising vaccine candidates from other pharmaceutical companies, The New York Times's Rebecca Robbins reports.Here's how the trials work:Late-stage vaccine trials are designed so that the faster participants get sick, the faster drug developers gain enough data to know whether their vaccines are effective.The trial ends after a certain number of cases — around 150 to 170 — have accrued. That number is chosen to make sure the results have sufficient statistical power to tell how well the vaccine works.For example, Moderna, which announced on Monday that an early analysis found its vaccine to be 94.5 percent effective, had planned for an outside panel to take a first look at its data after