The Los Angeles County Health Department revealed on Saturday that the dominant coronavirus strain in the area originated in the United Kingdom.

The department reported that the U.K. variant was detected more than half of the 40 specimens analyzed by the L.A. County Public Health Laboratory in the past week.

The lab also discovered the Brazilian and South African variants.

Two California variants were previously the most common strains circulating the county, the department noted, but testing in the past week did not detect either of the variants.

In the wake of these developments, the health department underscored the need for Los Angeles residents to continue to take measures to protect themselves, especially individuals who have not been vaccinated.

“The identification of these variants and the news of spreading variants from across the globe highlights the need for L.A. County residents to continue to take measures to protect themselves and others: this is particularly true for those who are not vaccinated against COVID-19 who can end up unknowingly being incubators of variants of concern,” the department wrote in a statement.

Health officials urged unvaccinated people to continue to wear masks and maintain physical distancing. They also called on these individuals to get inoculated “as soon as you can.”

California Gov. Gavin Newsom (D) announced last month that the state planned to lift almost all coronavirus restrictions and fully open its economy on June 15.

Health officials stood by this target date, even after the Centers for Disease Control and Prevention (CDC) announced that it is safe for vaccinated individuals to resume daily life without masks or physical distancing.

Last week, state Health and Human Services Secretary Mark Ghaly said in a statement that California will not lift its mask mandate until June 15, allowing a four-week period to give state residents "time to prepare for this change while we continue our relentless focus on delivering vaccines, particularly in underserved communities.”

Other states have already done away with mask mandates for fully vaccinated individuals in the wake of the CDC’s new guidance.

Last week, fully vaccinated New Yorkers were given the green light to go without masks in most places.

Beginning May 29, fully vaccinated people in Massachusetts will no longer have to wear masks or practice social distancing indoors or outdoors.