COVID's Omicron variant easier on lungs, but replicates 70 times faster than Delta: Study

Omicron variant of COVID-19 replicates nearly 70 times faster in human airways as compared to Delta but the overall infection in the lungs appears to be less severe than the original SARS-CoV-2 strain, according to the recent studies. A British laboratory research suggests that the B.1.1.529 variant may be less efficient in causing severe symptoms but is much faster at replicating in the lungs compared with the Delta and all other previous variants. 

Another study by the scientists at the Cambridge Institute of Therapeutic Immunology and Infectious Disease confirmed that the large cluster of mutations on the virus’s spike protein was able to effectively evade the antibodies developed from the previous infection. The variant also reduces the lung’s ability to neutralize and fight the disease which, among the vulnerable population, may result in severe COVID-19 disease. 

Omicron replicates much faster in the bronchus: Study

Researchers at the University of Hong Kong’s Faculty of Medicine meanwhile found that Omicron replicates much faster in particularly the bronchus that connects the windpipe to the lungs in just 24 hours after infection. This replication is several times faster than seen in the cases of Delta. Dr. Michael Chan Chi-wai and a team of researchers purport in their study which is yet to be peer-reviewed that Omicron infects human airways at a faster speed, which might relate to its transmissibility.

“It is important to 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,” Chan said in a statement. He insists that the highly contagious and mutated virus like Omicron, no doubt, might cause more severe disease and death simply by spreading much faster even when it may not cause bad infection in some. 

“Therefore, taken together with our recent studies showing that the omicron variant can partially escape immunity from vaccines and past infection, the overall threat from Omicron variant is likely to be very significant,” Chan warned. 

Meanwhile, Cambridge preprint, which was posted late on Friday night, suggests that Omicron demonstrates significantly lower infectivity of lung organoids and Calu-3 lung cells but gained immune evasion properties. The variant also compromises on properties associated with replication and pathogenicity, the harm caused to the body during the infection. “The Omicron spike protein induces relatively poor [lung] cell-cell fusion compared to Wuhan and Delta,” said Gupta in a tweet, announcing the findings. “The difference is significant.” He then explains that Omicron does appear to have become more immune evasive, but those properties associated with disease progression may be weakened over time.