VIRUS TODAY: Huge study on another COVID vaccine is underway

Here’s what’s happening Monday with the pandemic in the U.S.:

THREE THINGS TO KNOW TODAY

— A huge study of another COVID-19 vaccine candidate is getting underway Monday as states continue to roll out scarce supplies of the nation’s first shots. The candidate made by Novavax Inc. is the fifth to reach final-stage testing in the U.S. Some 30,000 volunteers are needed to prove if this vaccine — a different kind than its Pfizer and Moderna competitors — really works and is safe.

— Homicides in Detroit, New York, Philadelphia and other U.S. cities have topped 2019 numbers as violence surged during the coronavirus pandemic. Authorities and some experts say there is no one clear-cut reason for the spike. They point to social and economic upheaval caused by COVID-19, hostility toward police following George Floyd’s death in Minneapolis police custody, and a historic shortage of jobs and other resources in poorer communities as contributing factors. It’s happening in cities large and small, Democrat- and Republican-led.

— Nearly 1.3 million people went through U.S. airport checkpoints on Sunday, the highest one-day total in more than nine months, despite fear that travel will lead to more cases of COVID-19. The Transportation Security Administration said it screened 1,284,599 on Sunday, the most since March 15. More than 10 million people have traveled by air since Dec. 18, including six days with at least 1 million people getting screened. Dr. Anthony Fauci, the government’s top expert on infectious disease, said that level of travel could lead to a further increase in COVID-19 cases. Fauci said crowded airports make it difficult to maintain social distance, and holiday gatherings combine people from different households.

THE NUMBERS: The seven-day rolling average for daily new deaths in the U.S....