The new Omicron SARS-CoV-2 variant can infect the airways “faster and better” than the lungs, according to an experimental study.

The researchers at Faculty of Medicine at The University of Hong Kong used the technique of ex vivo cultures of the respiratory tract to study transmission of the Omicron variant and to find out differences, if any, from the ancestral SARS-CoV-2 and the Delta variant including severity of infection.

They found that compared to the ancestral virus and the Delta variant, Omicron replicated more rapidly in the human bronchus. The rate of multiplication was 70 times higher 24 hours after the infection suggesting a more efficient human to human transmission.

But in the human lung tissue, the Omicron variant replication was slower, more than 10 times lower, than the wild-type SARS-CoV-2 virus signifying a less severe nature of the infection. The authors also note that “the severity of disease in humans is not determined only by virus replication but also by the host immune response to the infection.”

However, at this point of time, we do not have enough details as the complete study has not been published and is undergoing peer review. Only a press release has been issued by the University of Hong Kong wherein Dr. Michael Chan Chi-wai, lead author of the study stated, “by infecting many more people, a very infectious virus may cause more severe disease and death even though the virus itself may be less pathogenic.” But this study has provided a clue about its high transmissibility.

Dr Tedros Ghebreyesus, WHO Director General has also cautioned about the exigency of the situation. He said, “Omicron is spreading at a rate we have not seen with any previous variant. We’re concerned that people are dismissing Omicron as mild. Surely, we have learned by now that we underestimate this virus at our peril.”

Preliminary evidence has shown that Omicron has potential immune evasion properties. And, given its high transmission rate, it’s not time to write it off, despite evidence of mild disease so far.

So, mask up (double masking), wash hands frequently, avoid crowds and ill-ventilated spaces and get vaccinated. This also calls for starting booster shots in the country.

Reference

1. https://www.med.hku.hk/en/news/press/20211215-omicron-sars-cov-2-infection, dated 15 December, 2021.