Preliminary laboratory data hints at what makes Omicron superspreading variant

Preliminary data hint at what makes Omicron spread so readily - STAT The finding "suggests much increased potential for aerosol generation during breathing,” said an expert on respiratory-virus dynamics. Megan Molteni STAT

Omicron is now in 77 countries, and moving faster than any previous strain of the coronavirus. In the U.K., where Omicron cases are doubling every two days, scientists believe it is behind this week’s record-setting surge in new infections.

The new variant is already causing about 13% of cases in New York and Washington states, just two weeks after Omicron was first detected in the U.S. Nationwide, it is hovering around 3% of total cases, but Omicron is rapidly eating into Delta’s dominance. And with insufficient testing and lag times in sequencing, it has likely gained even more ground than these numbers indicate.

But what exactly gives Omicron its competitive advantage has so far been unclear. Preliminary data, announced via press release Wednesday, which provide a first look at how Omicron may behave inside the human body, offers a clue to what might be behind its superspreading powers: more virus in people’s airways, which could mean more virus in the air.

The new research comes from a Hong Kong University team led by public health professor Michael Chan Chi-wai and pathologist John Nicholls. Previously, the researchers pioneered a method for growing human tissues extracted from the lung and respiratory tract, which they used to study how SARS-CoV-2 invaded cells and replicated compared to other dangerous coronaviruses. Using this same system, they analyzed how live, replicating particles of Omicron infected the tissues. They found that over the first 24 hours, Omicron multiplied about 70 times faster inside respiratory-tract tissue than the Delta variant. When they ran the same experiments with the lung tissue, they found Omicron was actually worse at infecting those cells than either Delta or the original strain of the virus that originated in Wuhan.