GENEVA - Experts from the World Health Organization (WHO) emphasized on Wednesday that vaccines are still highly effective against COVID-19, even new variants of the disease emerging in South Africa and the United States.

WHO data shows that global cases of COVID-19 are continually declining, with reported weekly deaths at their lowest level since March 2020. However, the Organization's Director-General Tedros Adhanom Ghebreyesus cautioned at a press briefing on Wednesday that these trends don't tell the full story.

"Driven by Omicron sub-variants, we are seeing an increase in reported cases in the Americas and Africa. The South African scientists who identified Omicron late last year have now reported two more Omicron sub-variants, BA.4 and BA.5, as the reason for a spike in cases in South Africa," he said.

"It's too soon to know whether these new sub-variants can cause more severe disease than other Omicron sub-variants, but early data suggests vaccination remains protective against severe disease and death," he added.

According to Maria van Kerkhove from the WHO's Health Emergencies Program, BA.4 and BA.5 have been detected in a number of countries. The WHO is still evaluating the severity of the two new variants.

However, van Kerkhove said it is not yet possible to confirm whether BA.4 and BA.5 have resulted in increased hospitalizations, as any rise in numbers could be due to a general spike in case numbers in South Africa. Nevertheless, she emphasized: "Vaccines still work incredibly well against preventing severe disease and death."

She also called for monitoring of, and testing for COVID-19 to continue in order for the WHO to be able to provide the public with the most accurate information and advice possible.