A second person has tested positive for the South African COVID-19 variant on Long Island.

Both variant cases so far were detected in Nassau County, according to Gov. Andrew Cuomo's office. The first case was confirmed two days ago in Glen Head.

Doctors say the South African strain is not more deadly, but could be more contagious.

"These variants emerging, it's raising a big, big question what will happen in the next few weeks and the next couple of months," says Northwell Health's Dr. Adrian Popp. "Will the transmission increase because the variants are more contagious? The answer would probably be yes."

The variant, known as B.1.351, was first detected in South Africa in December, and has since been found in dozens of other countries and at least 11 states in the U.S.

The variant carries mutations that help it latch on more tightly to human cells.

Genomic tests, which are more sophisticated than PCR tests, are the only way to detect variants of COVID-19.

"You cannot ask to be tested for this. What we can do is test for the regular variant of coronaviruses and subsequently these specimens are sent over to the specialize labs and a certain percentage of those are tested genomically, and this is the way to find out what kind of variant a certain person may have," says Popp.

Even as hospitalizations and positivity rates drop across the state, officials say it's a race to get more shots in arms before new variants, which might resist vaccines and spread faster than the original version of COVID-19, take hold.

Officials are urging people not to let their guard down. They say people have to continue wearing masks, social distancing and washing hands to reduce the risk of spread.

The Food and Drug Administration is working on a plan to approve updated vaccines if the variant surges in the U.S.