NICD covid-19 BA.2.75 COVID-19 XBB.1.5

COVID-19. Image: Twitter / @nicd_sa

XBB.1.5:  The ‘most transmissible’ COVID-19 subvariant detected in SA

The WHO said the XBB.1.5 subvariant is the most transmissible one detected yet. It has rapidly replaced other circulating variants in the US and some countries in Europe.

NICD covid-19 BA.2.75 COVID-19 XBB.1.5

COVID-19. Image: Twitter / @nicd_sa

The World Health Organization (WHO) states that the Omicron subvariant XBB.1.5 is the most transmissible subvariant detected since the start of the COVID-19 pandemic. The Kraken variant, as it has been nicknamed, was detected in South Africa on Friday, 6 January.


Professor Tulio de Oliveira, the Director of the Centre for Epidemic Response and Innovation (CERI),  said the first COVID-19 infection caused by XBB.1.5 was detected on Friday by Stellenbosch University’s Network for Genomics Surveillance in South Africa (NGS-SA).

The Kraken variant was found in an isolate taken on 27 December 2022. “At present, no increase in cases, hospitalisation or deaths. NGS-SA increasing genomics surveillance in South Africa…” said de Oliveira.


The WHO’s senior epidemiologist Maria van Kerkhove said XBB.1.5 is more transmissible due to mutations that allow it to adhere to cells and replicate quickly on Wednesday, 4 January. The WHO said the subvariant has been detected in 29 countries so far and there may be more.

“It does have immune escape, like we’ve seen with XBB but it is another subvariant of Omicron that is in circulation and the more this virus circulates, the more opportunities it will have to change,” said van Kerkhove.

The WHO expects further infection waves across the world; however, the health body added more infections doesn’t have to translate into further waves of death as current countermeasures continue to be effective.

“We don’t have any data on severity yet or on the clinical picture but we also do not have an indication that severity has changed with XBB.1.5. But, that is something that we are watching very closely through experimental studies in the lab but also in real-world data, when we look at hospitalisation rates around the world among people who are infected with this subvariant,” said van Kerkhove.

According to Reuters, the XBB.1.5. subvariant is an offshoot of XBB, which was first detected in October 2022. In the week of 31 December, XBB and XBB.1.5 accounted for approximately 44.1% of COVID-19 cases in the United States. The week before, it accounted for 25.9% of cases.