Weakness

The designer misinterpreted the CDC numbers for vaccinations administered and relabeled these as percentage of people who have received a vaccine shot. There is a difference between vaccinations administered, percentage of people who have received a single vaccine shot, and percentage of people who are fully vaccinated. Using the corresponding CDC data, for example:
Extracted from: Percent of People Fully Vaccinated Reported to the CDC - COVID-19 Vaccinations in the United States; US CDC Website; 4/30/2021 0600 ET accessed 4/30/2021.

And here’s how the CDC labels its corresponding chart:
[https://covid.cdc.gov/covid-data-tracker/#vaccinations]
Going back to the Yahoo News chart, I might have used a diverging color scale instead – perhaps at 50% to provide a reference point as we start to think about “herd immunity”.

Strength

The designer used a simple map of the United States and a continuous single color to show “percentage of people who have received a shot” (sic) along with a graduated bar to reference values at each end (52.9% - 90.3%). This made it easy to get an approximate sense of the relative % between states.

Bonus points for allowing the user to hover over states to get more details.

However, this does not justify or cancel out the weakness pointed out earlier.

Sources

Covid-19 Vaccinations in the U.S.; Covid19 “By the numbers” landing page for Yahoo News; Yahoo News Website; Accessed 4/30/2021
https://news.yahoo.com/coronavirus
https://github.com/yahoo/covid-19-data

Total Doses Administered Reported to the CDC - COVID-19 Vaccinations in the United States; US CDC Website; 4/30/2021 0600 ET accessed 4/30/2021
https://covid.cdc.gov/covid-data-tracker/#vaccinations

Percent of People Fully Vaccinated Reported to the CDC - COVID-19 Vaccinations in the United States; US CDC Website; 4/30/2021 0600 ET accessed 4/30/2021
https://covid.cdc.gov/covid-data-tracker/#vaccinations

Hicks, Lucy; FAQ: Herd Immunity and COVID-19; WebMD Website; 4/14/2021 accessed 4/30/2021
https://www.webmd.com/vaccines/covid-19-vaccine/news/20210414/faq-herd-immunity-and-covid-19

Lipsitch, Marc; COVID-19 Vaccines and Herd Immunity; Harvard School of Public Health Website; 12/17/2020 accessed 4/30/2021
https://ccdd.hsph.harvard.edu/2020/12/17/covid-19-vaccines-and-herd-immunity/