Two new even more transmissible Omicron subvariants have been found in the United States, Deadline reports

First identified in South Africa, BA.4 and BA.5 were initially recorded on Jan. 10 and Feb. 26, respectively, but have only recently caused a dramatic spike in cases in their country of origin. Abdool Karim, public health expert at the University of KwaZulu-Natal, tells NBC News that the impact of the new subvariants have led to a slight rise in hospitalizations and no increase in deaths. 

However, as has been the case with each previous subvariant, the highly transmissible nature of the virus has caused a spike in cases in South Africa. The positivity rate in the country has risen from four percent in mid-April to 19 percent, as of Thursday. Cases climbed from a few hundred just a few weeks ago to 6,000 per day.

Despite the surge in numbers, Karim said “it’s too early to tell whether BA.4 is going to cause a fully-fledged wave.” 

According to Deadline, there have only been 10 recorded cases of BA.4 and four cases of BA.5 in the United States, but that number is likely to rise given the highly transmissible nature of the virus.

Data released last month shows nearly 60 percent of people in the U.S. have already been infected with Omicron or another COVID variant, including three in four children. In December, the CDC reported about one-third of the country’s population had caught Covid, prior to the emergence of these subvariants. 

CDC Director Rochelle Walensky said in a statement that due to people getting vaccinated and boosted, as well as prior infection, she believes there is “a lot of protection” in the country, adding that “we cannot underscore enough, those who have detectable antibodies from infection, we still encourage them to get vaccinated.”