U.S. details vaccine efficacy, plans use of booster shot against wildness of COVID-19

A man sits beside white flags placed on the National Mall to honor the lives lost to COVID-19 in Washington, D.C., the United States, Sept. 18, 2021. The United States has kept on pushing through federal requirements of broad vaccination by highlighting the efficacy of its three authorized COVID-19 vaccines, while planning to narrow the use of a booster shot only to old people and those who work at high risk. (Photo by Aaron Schwartz/Xinhua)