Fresh research out of the University of Tokyo has demonstrated that the Omicron variant of Covid-19 replicates more slowly in the lungs than the previous Delta variant, which may explain why it has been causing less severe infections in the population. The findings prove some relief even as scientists work to decide the highly-mutated virus.
The study, which was conducted in hamsters, has confirmed the results of a Hong Kong study that came out in December 2021, which reported that Omicron replicated up to ten times more slowly than Delta in the lunga. However, the Hong Kong study analysed tissue samples from patients, which showed that the replication of Omicron was 70 times higher in the parts of the lungs called the bronchi, lending a possible explanation for its rapid spread and high infectiousness.
Despite being highly infectious, the new variant is not causing severe illness like its predecessors. In Britain, where Omicron is not the dominant variant in those infected with Covid-19, hospitalizations have risen but the number of patients needing mechanical ventilation beds has also remained steady through December, unlike previous peaks in the pandemic.
The analysis was published by the UK Health Security Agency, after it worked alongside Cambridge University MRC Biostatistics unit to analyse 528,176 Omicron cases and 573,012 Delta cases.
In addition to this, data published by the American Academy of Pediatrics has shown that while 199,000 children in America were hospitalised between between December 16-23 in 2021, the rates of severe illness were far lower than in older populations.
In an interview with The Associated Press, Dr. Rochelle Walensky, director of the American Centers for Disease Control and Prevention said that the cases of Omicron detected in the US so far were "mild".
"What we generally know is the more mutations a variant has, the higher level you need your immunity to be. ... We want to make sure we bolster everybody's immunity. And that's really what motivated the decision to expand our guidance," Walensky said, referencing the recent approval of boosters for all adults.