The U.S. Virgin Islands’ active Covid-19 cases grew by twenty-seven in one day, from 165 to 192 active cases between Tuesday and Wednesday, according to the V.I. Dept. of Health.

The surge comes as health officials confirm the presence of the Delta variant in the U.S. Virgin Islands. “With this surge in positive cases there is a greater chance for the virus to mutate. Identifying this variant in one district only indicates to us that it has already covered the whole territory as inter-island travel heightens the spread,” D.O.H. said Wednesday.

As of Wednesday, there were 192 active Covid cases in the USVI: 63 on St. Croix, 125 on St. Thomas, and 4 on St. John. The risk factors in the territory were close contact and community spread, according to D.O.H. data.

As of Monday, there were sixteen Covid patients at the territory’s hospitals, with the Schneider Regional Medical Center accounting for eleven, and the Juan F. Luis Hospital, five. At least two patients were ventilated at SRMC and one at JFL.

Scientists say the Delta Covid strain, also known as the B.1.617.2 variant, appears to have two advantages over earlier forms of the virus: it is more infectious and appears to be more effective at evading vaccines, though people who are fully vaccinated have significant protection against Covid. The strain is 40-80 percent more contagious that the Alpha (original).

Last month, about half of adults infected in an outbreak of the Delta variant in Israel were fully inoculated with the Pfizer Inc. vaccine. This reality prompted the Israeli government to reimpose an indoor mask requirement and other measures to contain the highly transmissible strain.

Governor Albert Bryan on Monday encouraged residents to take precautions and follow Covid guidelines. He also pushed hard for vaccination, and said if Covid-19 numbers remain elevated, restrictions would be reintroduced, among them a decrease in capacity for gatherings.

As of Monday, 48.1 percent of the USVI population is vaccinated against Covid, which equates to 38,220 residents. D.O.H. said 70 percent of the population needs to be vaccinated in order to achieve herd immunity.

Mr. Bryan also said the Covid-19 Task Force will be stricter in enforcing rules. He said the administration has worked with the public, including owners of establishments such as bars and restaurants to be more lenient when Covid numbers are trending lower. However, with the positive cases rising and the Delta variant afoot in the territory, leniency is being abandoned — at least for now — for more active enforcement, according to the governor.