The US has reported its first cases of the more infectious coronavirus variant from South Africa

• South Carolina officials announced Thursday they had detected two coronavirus cases involving the more infectious variant first found in South Africa.
• It's the first time this variant has been found in the US.
• Some evidence suggests existing vaccines may be less effective against the variant.

The US has reported its first cases of a more infectious coronavirus variant first found in South Africa.

South Carolina health officials announced Thursday that they had detected two cases involving the variant, named B.1.351, this week.

Both people infected with the variant are adults, one from the Lowcountry and one from the Pee Dee region of the state, according to a press release from the state department of health and environmental control (DHEC).

B.1.351 was discovered in October in South Africa and has since spread to 31 countries.

There's no evidence that suggests the variant is deadlier than other versions of the coronavirus, however it can "spread more easily and quickly," according to the Centers for Disease Control and Prevention. The variant has mutations in its spike protein - the part the virus uses to invade cells - which contribute to its increased infectiousness.

Preliminary research published last week suggested the variant can partially evade the defenses current vaccines build in our bodies' immune systems. Pfizer and Moderna, however, both say their vaccines will work again B.1.351.

The US isn't testing enough samples to spot variants quickly

Neither South Carolinian infected with the variant had recently traveled, and there was "no connection between these two cases," state health officials said.

This suggests, in all likelihood, the variant entered the US long before these infections were detected and has been spreading silently for weeks.

"It's probably more widespread" in the state, Dr. Krutika Kuppalli, an infectious diseases physician at the Medical University of South Carolina, told the AP.

Countless versions of the coronavirus are circulating worldwide, each separated by a handful of tiny changes in its genome. To keep tabs on these variants, researchers must genetically sequence samples of the virus.

According to the DHEC, South Carolina researchers have been testing random samples "in order to identify any instances of the variant viruses" since June.

But the US is painfully far behind in its sequencing efforts. The country genetically sequences less than .01% of its coronavirus cases: only 3 out of every 1,000. That's likely the reason the US missed the new strain's introduction.

"Believe it or not, we are 43rd in the world at genomic sequencing," Jeff Zients, coordinator of the president's COVID-19 task force, said during a White House briefing on Wednesday, calling the situation "totally unacceptable."

Increasing sequencing efforts is critical to the US's efforts to monitor the introduction of new strains like B.1.351, Zients said, because that "will allow us to spot variants early, which is the best way to deal with any potential variants."

Researchers in Minnesota spotted the first US case of the P.1 variant, first detected in Brazil, on Wednesday. At least 315 cases of the B.1.1.7 variant from the UK have been reported in 28 states since December 29. Both those variants have similar mutations in their spike proteins which make them more infectious too.

Hilary Brueck contributed reporting to this story.