1. GISAID. Tracking of variants https://www.gisaid.org/hcov19-variants/: Accessed July 9 2021,.
2. Where are the newest COVID hot Spots?;Stein,2021
3. Here's a map showing where low vaccination rates meet high case counts as U.S. Covid infections surge;Rattner;CNBC,2021
4. As COVID cases rise all over U.S., lower vaccination rates point to worse outcomes;Leatherby,2021
5. Spread of delta variant ignites covid hot spots in highly vaccinated parts of the U.S., post analysis finds;Nirappil,2021