COVID-19 was the number one cause of death for people between the ages of 35 to 54 during some months since the pandemic began last year, according to recent data. Meanwhile, as the Delta variant continues to drive infections around the world, the push for booster shots in the U.S. has raised concerns since many are still awaiting their first dose. ProPublica's Caroline Chen joins. PBS NewsHour is supported by - https://www.pbs.org/newshour/about/funders