Arizona is now allowing anyone over the age of 16 who wants to get vaccinated against COVID-19 to get their shots.

Some states are taking a similar approach, while others are more restrictive. And new research finds the states who are limiting who can get the vaccine are getting it into residents' arms more efficiently.

To find out how and why, The Show spoke with Nicholas Stewart, senior research scientist at the nonprofit Surgo Ventures, which did the research.

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