As the highly contagious Delta variant rages across the world, some countries are offering a third COVID-19 shot to slow down the spread. Meanwhile, the U.S. CDC said the "war has changed" against COVID-19 because the Delta variant is as contagious as chickenpox. 

For more on the raging coronavirus variant, CGTN talked to Chen Xi, assistant professor of Health Policy and Economics, Yale School of Public Health. He is also the President of China Health Policy and Management Society. He said that selected groups of recipients may require a booster dose and administration of third jabs could cause not only vaccine shortage within a country, but on a global scale. He also shared his view on the infectivity of the Delta variant.