Despite high levels of population immunity, the World Health Organization (WHO) has expressed concerns regarding the COVID-19 Omicron variant, XBB.1.5 (a recombinant of XBB). In early December, 10% of COVID-19 cases in the US were caused by XBB.1.5. Four weeks later, the new strain is now responsible for 28% of COVID-19 cases in the US, making it the dominant strain in the country, according to the Centers for Disease Control and Prevention (CDC). Although the WHO noted that there is no indication that this variant is more serious than others in terms of symptomology and mortality, XBB.1.5 has an enhanced transmissibility that could be cause for concern.

The current head of virology at Imperial College London, Professor Wendy Barclay, reports that XBB.1.5 has a mutation that restores the ability to bind to cells while continuing to evade immunity, known as F486P. This could contribute to increased transmission of COVID-19, despite the level of herd immunity that has been established globally. Barclay also added that these evolutionary changes in the virus help it to evolve and find new ways of bypassing the body’s defense mechanisms.

Due to concerns about XBB.1.5, it is important that vulnerable populations are protected from the virus. According to GlobalData, approximately 70% of the US population is fully vaccinated (completed primary series). Furthermore, 68.9% of people older than age 65 years in the US received their first booster dose, but only 40.1% have received their third dose. Increasing the momentum of vaccination schemes throughout the US and encouraging people to engage in booster programs may help to slow down the spread of this new XBB.1.5 variant.

In December 2022, the US government re-introduced free at-home COVID-19 tests to help prevent the increased transmission of the virus that the country is expected to experience throughout the winter months. Initially, the government stated that there will be 15,000 free community testing sites across the country, but this number may need to increase over the coming months due to the escalating transmission of the XBB.1.5 variant. It is of paramount importance that the US government, and other governments globally, should emphasize the importance of testing and vaccination to prevent a spike in COVID-19 infections.