The COVID-19 Delta variant — a highly transmissible strain — continues to spread throughout the country. Pennsylvania, however, remains one of the most protected states, given its high vaccination rate. Erika Fry and Nicolas Rapp reported the statewide level of protection for Fortune.

So far, studies show that vaccines are effective against this variant. Its presence therefore becomes pertinent to those ignoring vaccination recommendations. They are now highly susceptible to the Delta strain.

The biological offshoot of the coronavirus currently represents 13.1 percent of all new cases in Pennsylvania and the Philadelphia region.

Unfortunately, the number of unimmunized Americans remains stubbornly high, despite abundant vaccine supplies.

Through June 22, at least one shot of the COVID-19 vaccine was administered to 177.9 million U.S. citizens (53.6 percent of the population). Moreover, 150.8 million people have received both doses.

A drill down look at state-by-state rates, however, reveals disparities.

Pennsylvania fortunately has one of the highest rates of vaccinated adults (74.7 percent). This puts the Keystone State at eighth in the top-ten state populations vaccinated.

Read more about current vaccination rates in Fortune.