The COVID-19 pandemic is characterized by the highly infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Omicron variant, which was first reported in Botswana and quickly spread as the dominant variant worldwide during early 2022, the start of 2023 brings a new subvariant of the Omicron variant of SARS-CoV-2, known as XBB.1.5. The Omicron XBB.1.5 subvariant is a sublineage of the XBB variant, a recombinant of two BA.2 sublineages, with an additional spike receptor-binding domain (RBD) change, S486P.
It is demonstrated that XBB.1.5 is just as immunologically evasive as XBB.1, the Omicron subvariant with the largest immune escape to date, using pseudotyped viral neutralization experiments. There is currently no data on real-world vaccine effectiveness against severe disease or death. At this time, there are no indications that XBB.1.5's infection severity differs from that of earlier Omicron sub-lineages that were circulating. The gold standard for COVID-19 diagnosis is reverse transcription-quantitative polymerase chain reaction (RT-qPCR) testing using upper respiratory tract swabs or saliva. there are no vaccine effectiveness (VE) estimates for XBB.1.5 yet, no specific data are currently available on the effectiveness of COVID-19 antiviral therapeutics.