New Research Points to Why Omicron is Spreading More Rapidly

As the Omicron variant of the SARS-CoV-2 virus sweeps much of the globe, scientists are digging into why this particular mutation is spreading even more rapidly than its predecessors.  

The primary difference found by the latest research out of The University of Hong Kong, yet to be peer reviewed, is that the Omicron variant multiplies faster in airways, slower in the lungs. Omicron replication outpaced the Delta variant and the original SARS-CoV-2 strain 70 times over in tissue lining the airways. It also reaches higher levels of spread in the respiratory tract tissue than Delta, just 48 hours after infection. 

Yet, much to the world’s relief, Omicron seems to be making people less severely ill than previous mutations. Scientists believe it relates to the discovery that the variant multiplies approximately 10 times more slowly than the original SARS-CoV-2 virus in the lungs, lowering disease severity.  

Dr. Michael Chan Chi-wai, a principal investigator on the findings said, “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, which may lead to dysregulation of the innate immune system, i.e. ‘cytokine storm’.” 

Omicron has dozens of mutations that make it a more “slippery foe” for our immune system’s neutralizing antibodies to recognize and attack. While the power of the currently approved vaccines is diminished in the face of this variant, another study focused on the Pfizer-BioNTech vaccine found that the shot still afforded some protection against the virus and booster shots could be a key component. 

“It is also noted that, 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. 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 said. 

The Omicron variant is 4-fold more infectious than the original strain of SARS-CoV-2 that rocked the world and 2-fold more infectious than Delta. The spike protein, which binds the virus to human cells, on this latest strain is much better at getting the virus access to human cells than that of the original.  

Omicron is already surging across the globe. As of December 4th, the U.S. only had about 0.4% of cases caused by the variant. That was a mere three days after the first Omicron case was identified in the states from a fully vaccinated person who had traveled from South Africa. In just a week, that number has jumped sevenfold, to almost 3%. That number is rapidly rising. Experts believe the percentage will approach 20% by the time the numbers are posted next week. 

Federal health officials warn that the variant’s rapid spread could peak in a massive wave of infections, mainly as groups gather for the holidays and the population spends increasing time indoors. The UK and other European countries are already imposing restrictions. France has banned nonessential travel with the UK over the Omicron surge.  

The scientific community is both intrigued and cautious about these latest findings. The infected tissues measuring spread in airways versus lungs was done in a lab, which can’t quite match the in-body, human response. More study is needed, and, with the rapid spread of Omicron, certainly forthcoming.