HONOLULU (AP) — Hawaii health officials said Friday that the more transmissible and potentially more harmful delta variant of COVID-19 has been detected in all four of the state's major counties.

The state Department of Health has found 13 cases of the delta variant so far, including seven or eight that related to people who have traveled from out of state. There is also evidence of community spread of the variant.

The cases were from specimens collected between May 31 and June 10.

Preliminary research shows the delta variant results in a higher rate of severe illness than other strains of the disease, the department said.

Currently available vaccines against COVID-19 have been shown to be effective at helping prevent people from spreading the variant and getting severely ill as a result of it.

Kauai District Health Officer Dr. Janet Berreman urged people to get vaccinated.

“It’s really important not only that people who haven’t been vaccinated be vaccinated, but that they don’t delay being vaccinated because every additional week is a chance for this virus to take hold even more strongly in our community and spread even more quickly,” Berreman said during a news conference. “So time is really of the essence.”