More than half of the residents of Windemere Nursing and Rehabilitation Center and several staff members have contracted a new highly contagious variant of COVID.

Symptoms for the 18 residents and eight staff who tested positive are varied, but none are so ill that they require hospitalization, the hospital wrote in a statement on Wednesday. The cause of the spread is unknown, but the prevalence of the new variant, known as XBB.1.5, shows it is active on the Island.

There are 30 residents in total at Windemere, and their families have been notified about the outbreak, the press release stated. Federal guidelines for visitation are being followed, and patients who have tested negative have been isolated to help prevent further spread. Infected staff are isolating in their homes.

Residents and the staff who have tested negative are being tested daily to monitor the spread of the virus, the statement continued.

Medical officials continue to stress the use of preventive measures to reduce the spread of this highly contagious new strain of COVID, including wearing masks in crowded public spaces and good hand hygiene. Strict masking policies remain in place at the hospital and the home.

The XBB.1.5 variant caught virologists attention in the last few months because it has more mutations to evade immunity than any other variant, Johns Hopkins School of Public Health wrote earlier this year. According to Martha’s Vineyard Hospital, the variant now accounts for 40 percent of COVID cases.