Why IS Omicron so contagious?

With newer restrictions and rising anxiety levels with each passing day, the Omicron virus variant has been a hellhole of shock and cause of concern. With the variant reported in more than sixty countries in total, it is alarmingly evident that one must take isolation precautions and Covid protocols more seriously than ever before.

In South Africa itself, over fifty mutations of the Omicron variant have been identified. It is also here we have found conclusive evidence of it being able to infect survivors of the previous SARS-CoV-2 versions and those vaccinated against it. So, why is this variant so contagious? What makes Omicron so transmissive and able to evade our immune systems so well?

Usually, the general criteria to compare the contagiousness of viruses is to look at their transmissibility rates as well as how good they are at evading the host's immune system. Researchers are looking primarily into these features to understand the situation better.

Scientists are still racking their brains as to what exactly makes the variant such a lighting-fast one: it has outcompeted its predecessor, the delta variant, giving us the effective reproduction number at 3.7, which means that one case of omicron sparks at least three other new infections on average. So far, one primary reason they have come up with is its immense ability of "immune escape/evasion", with its many mutations on the spike protein, allowing it to infect our cells more efficiently than any of the previous variants. An interesting possible confirming point for this hypothesis is that the rates of infection of the delta and Omicron variants have not shown a significant difference for unvaccinated people. If this can be confirmed with more data, we can conclude that while the delta and omicron variants are equally transmissible, Omicron is much better at immune evasion.

But to be fair, with so many mutations as it has, Omicron may have multiple other advantages up its sleeve. Speculations about its replication rates, incubation period and other life cycle factors abound. Researchers also discovered that it multiplied around 70 times faster than delta in the bronchi tissue samples. At the same time, Omicron had much more trouble infecting cells in lung tissue than the original version of the coronavirus.

With science communicators like ourselves trying to get out as accurate information as we can, WHO Communications itself invited Dr Maria Van Kerkhove to update us on the variant's transmissibility, symptoms, severity and precautions one must take to protect oneself. In contrast to the previously stated hypothesis, she says, "some of the mutations that are identified in Omicron will provide a growth advantage [and] will allow it to be more transmissible". "Second, is that we have what is called an immune escape. And this means that people can be reinfected either if they had a previous infection or if they've been vaccinated," she said. She went on to list a third possible reason: the virus replicates "in the upper respiratory tract -- and that's different from Delta and other variants, including the ancestral strain which replicated in the lower respiratory tract, in the lungs."

On a side note, studies suggesting that Omicron can partially escape vaccine immunity mean that the overall threat from the variant "is likely to be very significant." We can do individually as of now to follow social distancing protocols meticulously and diligently keep ourselves updated on the new research news related to the same.