The World Health Organisation (WHO) is reported to have identified another immune-evasive COVID variant, XBB, which has already spread to 26 countries. The infection rate of this new version of the COVID is increasing among the populations of both Singapore and Bangladesh. This only points to the immune-dodging potential of this variant of the pathogen as the population of Singapore is fully vaccinated with booster doses. The level of vaccination is also high in Bangladesh. Researchers at the Department of Genetic Engineering and Biotechnology of Chittagong University have meanwhile found the existence of XBB as well as BM.1.1.1 subvariants of Omicron from samples taken from 12 patients. The patients of these subvariants, however, did not show any severe symptoms except slight fever and cough.
In this connection, the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b) has also reported the findings of its research done between September 10 and October 14, 2022. In the research, the organisation sequenced 92 SARS-CoV-2 genomes and found that the virus was still evolving. During the first two weeks of their genome sequencing, the icddr,b scientists identified 84 per cent of the viruses as Omicron BA.2, while 16 per cent as BA.5. But those subvariants were soon replaced by the earlier noted new variant, XBB, and in the last three weeks (September 24 to October 14) of the study, this subvariant was found to be prevalent (85 per cent of the viruses) among the population.
The previously mentioned other subvariant (BM.1.1.1) as found by the Chottogram University researchers was also identified by the icddr,b researchers. However, 78 per cent of the cases were infected with XBB, according to icddr,b findings. And the disease symptoms were found to be moderate among those infected with the virus (XBB). But the few who had severe symptoms were hospitalised. 66 per cent of those hospitalised had fever, 50 per cent had cough, 44 er cent had headache. 41 per cent of the patients complained of body ache and pains, 37 per cent had runny nose, while another 37 per cent had reported that they were feeling weak. And 47 per cent of the patients were found to be cases of reinfection.
The hospitalised cases, though they represented a small percentage of the XBB-infected patients under the study, should be cause for concern. This is for the simple reason that the subvariant (XBB) of the Omicron is still in the process of evolving. According to Global Initiative on Sharing Avian influenza Data (GISAID), descendants of XBB like XBB.1, XBB.2 and XBB.3 have been identified in the US, especially in the New York State. WHO, on the other hand, reports that the number of XBB.1 cases were more prevalent. Actually, they (XBB.1 patients) were three times the number infected with the parent XBB. However, whether XBB spin-off such as XBB.1 is more evasive or transmissible than their parent-- XBB, is still not known. Time will tell, if the small change in the spike protein found in XBB.1 gives it any advantage over its parent variant, the XBB. Though the level of threat posed by XBB and its progeny are not clear, its extraordinary ability to evade immunity is keeping scientists on their toes.
Epidemiologists, especially, the US's top infectious diseases expert, Dr Anthony Fauci, is expecting a wave of COVID infection in the US during this fall and winter. But scientists are not still sure which of the different COVID variants would trigger the wave. Omicron XBB cases are reportedly on the rise in different countries including India, England, U.S., Singapore, Hong Kong, Canada, Australia and Denmark. Since Bangladesh is also among the countries experiencing XBB infection, the health department here should be on the alert and take necessary measures to control the pathogen's transmission among the population.
sfalim.ds@gmail.com