An adult in South Carolina’s Lowcountry region has become the state’s first confirmed case of the United Kingdom COVID-19 variant, South Carolina’s Department of Health and Environmental Control said.

The person "has an international travel history," the department said.

The U.S. has confirmed at least 434 cases of the B.1.1.7 U.K. variant across 30 states, South Carolina officials said.

"Experts agree that existing vaccines work to protect us from this variant, even if we don’t know just how effective they are," the South Carolina officials said. "At this time, there’s no conclusive evidence to prove that the B.1.1.7 variant causes more severe illness."

ABC News’ Josh Hoyos contributed to this report.

The Coachella Valley Music and Arts and Stagecoach Country Music festivals, set for April, were canceled on Friday by Dr. Cameron Kaiser, health officer for Riverside County, California.

Riverside County’s positivity rate stands at 20%. The county has 0% bed availability in its intensive care units.

January has been the deadliest month since the pandemic began, with 90,844 total deaths, according to data compiled by Johns Hopkins University.

The U.S. coronavirus death toll stands at 436,810 -- with the Center for Disease Control and Prevention projecting that more than 77,000 deaths could be reported by Feb. 20.

California is now the second U.S. state with known detection of the Brazil P.1 variant.

Minnesota health officials confirmed earlier this week the nation's first known COVID-19 case associated with the variant.

Inside Stanford's Clinical Virology Laboratory, Dr. Benjamin Pinsky and his team found two strains of the virus: the Brazil strain and the U.K. strain, KGO reported Saturday morning.

"It's in about 17% of the samples that we've sequenced," Pinsky told KGO.

Laboratory experiments that tested Moderna's COVID-19 vaccine against new variants of the novel coronavirus show little to no impact on its efficacy, according to a press release from the company.

The vaccine produced antibodies that neutralized all key emerging variants tested, including B117 and B1351, which were first identified in the United Kingdom and in South Africa, respectively. The study showed "no significant impact" on neutralizing titers against the B117 variant. Meanwhile, a six-fold reduction in neutralizing titers was observed with the B1351 variant but remain above levels that are expected to be protective, according to the press release.

Although the two-dose regimen of the vaccine is expected to be protective against emerging strains to date, Moderna announced Monday that it will test two additional strategies: one to explore whether adding an extra dose could offer more protection, and another to study a version of their original vaccine that's more tailored to the South Africa variant.

"As we seek to defeat the COVID-19 virus, which has created a worldwide pandemic, we believe it is imperative to be proactive as the virus evolves. We are encouraged by these new data, which reinforce our confidence that the Moderna COVID-19 Vaccine should be protective against these newly detected variants," Moderna CEO Stephane Bancel said in a statement. "Out of an abundance of caution and leveraging the flexibility of our mRNA platform, we are advancing an emerging variant booster candidate against the variant first identified in the Republic of South Africa into the clinic to determine if it will be more effective to boost titers against this and potentially future variants."

ABC News' Sony Salzman contributed to this report.