Nation CDC studies point to reasons behind vaccination slowdown; Moderna to add production lines: Latest COVID-19 updates June 22, 2021 Elinor Aspegren and Steven Vargas, USA TODAY Comments Off on CDC studies point to reasons behind vaccination slowdown; Moderna to add production lines: Latest COVID-19 updates Young Americans are less likely to get vaccinated against COVID-19 than their elders, a new CDC study showed. Latest coronavirus news.