SPRINGFIELD, Ill. (WTVO) — Illinois Gov. JB Pritzker is encouraging people to wear masks indoors — even if they’re received a COVID-19 vaccine — in an effort to halt the spread of the more-contagious Delta variant of the virus.

At a press conference on Monday, the Governor also urged unvaccinated residents to get the shot.

“This is very real. I implore all residents: If you have friends and family on the fence, share with them the life-saving benefits of these free vaccines and encourage them to remain masked until they are fully vaccinated,” he said.

Earlier this week, the World Health Organization warned about the spread of the latest variant, saying even fully vaccinated people should wear masks to prevent transmission.

“This virus is very much present, infecting people, hospitalizing some and tragically, killing others every day. Israel, which has led the world in vaccinations has reinstated its indoor mask mandate, and other mitigations in light of fully vaccinated adults getting infected with the Delta via variant,” Pritzker said.

The Delta variant is a highly contagious, and potentially more severe, strain of the coronavirus first discovered in India.

The Center for Disease Control and Prevention has not yet issued federal guidance calling for vaccinated people to wear masks, but has labeled the Delta variant a “variant of concern,” saying “there is evidence of an increase in transmissibility, more severe disease … significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines.”

Only 84 cases of the Delta variant have been reported in Illinois so far, but Pritzker said it is expected to be the dominant strain by the fall.

So far, 48% of the state’s population has received a vaccine.