Some states — particularly those in the South — are at much higher risk for bad coronavirus outbreaks not only due to low vaccination rates, but also because their populations were more vulnerable to begin with.

Why it matters: In many ways, the pandemic feels over in the U.S. But in some parts of the country, that feeling may be short-lived, especially as new variants continue to spread.

Driving the news: Although experts are concerned about the growing prevalence of the Delta variant in the U.S., evidence is accumulating that vaccines work well against it.

• "The Delta variant accounts for a rapidly rising proportion of US cases, and that proportion will continue to grow and could cause clusters and outbreaks, particularly in areas of the country and in demographic groups that have lower vaccination rates," tweeted former CDC director Tom Frieden.
• The virus will continue to evolve as long as it's given the opportunity to continue spreading around the world.

Between the lines: Certain risk factors, like a high rate of underlying conditions or poor access to health care, make some communities more vulnerable to severe outbreaks than others.

• Arguably, people who live in these areas would benefit most from vaccination, as they're at highest risk.
• But that's not what's happening. Instead, some of the most vulnerable states in the country — like Alabama, Mississippi and Georgia — have some of the country's lowest vaccination rates, according to an analysis by Surgo Ventures.

The bottom line: Until vaccines were widely available, Americans suffered through the pandemic together.

• Going forward, most of the suffering will likely be concentrated among people who remain unvaccinated.