The National Institute for Communicable Diseases (NICD) issued a statement about the XBB.1.5 subvariant on Wednesday, 11 January, in the wake of the briefing called by the Department of Health on Tuesday.
XBB.1.5 ONE OF HUNDREDS OF OMICRON SUBLINEAGES IN SA
XBB.1.5 is one of more than 200 Omicron sublineages circulating in South Africa, said the Institute.
“The XBB sublineage has been shown to have increased immune evasion compared to previous sublineages.
“Since its identification, the XBB sublineage has given rise to several more sublineages, including XBB.1, XBB.2, and XBB.3, that have been circulating in South Africa since October 2022,” said the NICD.
XBB.1.5 was first detected in October in the United States and has been seen in several other countries since then.
The first detection in South Africa came from an anonymous sample collected on 27 December 2022. The NICD said the local detection was not unexpected.
“XBB.1.5 has been shown to have a growth advantage in the USA compared to previous variants, which means it may outcompete other variants to become the dominant circulating variant in some settings,” said the NICD.
The Institute subvariant may not necessarily “result in a large wave of infections” due to the widespread circulation of other Omicron sublineages in South Africa and the overall high population immunity.
‘SUBVARIANT OF CONCERN’
XBB.1.5 is now being monitored as a “subvariant of concern” and its transmissibility is thought to be due to a substitution (F486P) in the spike protein, which increases its ability to bind the virus to the human ACE2 receptor.
The NICD said it is not yet known whether the subvariant will cause a more severe COVID-19 infection compared to other Omicron sublineages. The World Health Organization (WHO) Technical Advisory Group on Virus Evolution is currently busy with an ongoing risk assessment of the subvariant.
The NICD continuously tracks variants circulating in South Africa and publishes the information on a weekly basis on its website ( ).
All private and public laboratories are requested to send positive COVID-19 specimens for genomic sequencing.