Pune: A six-month-long study of the health impact from Omicron subvariants and the recombinant XBB have found that the latter mostly led to only mild symptoms in patients with Covid-19, XBB, identified in August last year, had sparked widespread concern due to its fast spread in India and other parts of Asia.
The study, conducted by experts from BJ Medical College, the National Institute of Virology and Indian Institute of Science Education and Research (IISER), Pune, analyzed 494 patients infected by Omicron subvariants BA.2.10, BA.2.38, BA.2.75, BA.5, BQ.1 and XBB, which is itself a recombinant of BA.2.10.1 and BA.2.75. A good 97% of these patients survived the infection, the analysis found.
The research also said XBB’s virulence, or its ability to cause disease, was comparable to that of other Omicron subvariants, which are known to cause mostly mild Covid. These findings, the researchers said, are consistent with an in vivo study in hamsters where XBB was found to be less pathogenic than the Delta version which had triggered the deadly second wave of Covid in 2021.
The researchers added that the intrinsic pathogenicity of the XBB variant and its efficiency in infecting the lungs was comparable to, or even lower, than BA.2.75’s.
XBB, Omicron variants mostly trigger mild Covid-19: Study
Dr Rajesh Karyakarte, Maharashtra’s coordinator for genome sequencing and a senior scientist with BJ Medical College told TOI that the study was the first of its kind in India that analyzed the full range of symptoms associated with the new virus variants..
“There were concerns about the potential severity of infections caused by these variants due to multiple mutations. But our data suggests XBB may be milder than both Omicron’s BA.2.75 and Delta, at least in India,” Dr Karyakarte said. He added, “This could be indicative of an assumption made by some scientists that as more and more versions of Omicron emerge, they seem to get milder.” Dr Karyakarte, however, said it’s still unclear if it was vaccination, previous exposure or an actual drop in the intrinsic pathogenicity of SARS-CoV-2 that had led to mild cases in India.
The study also found that compared to the 66.6% of patients with BA.2.38 and 75% of those with BA.2.75, 78.8% of XBB patients went on to recover at home, without needing hospital care. Nearly 19.05% and 6.46% of patients with BA.2.38 and BA.2.75, respectively, needed supplemental oxygen. This percentage in XBB patients was even lower, at just 4.7%. Another key takeaway from the study was protection offered by vaccines even against new variants.
“Out of 488 cases with vaccination data, 449 had at least one dose. Of these, 97.5% survived (either with or without hospitalisation). Of the 40 who were unvaccinated in the study, 90% survived and 10% did not. So We urge those who’ve not taken their boosters to do so immediately,” Dr Karyakarte said.