From a bit of a online review, Health official and scientists around the world along with the health officials in Australia are now in the main indicating that the Delta Variant is more transmissible, and that people can become infected from briefer exposures.
But why is it so? Well no-one exactly knows as yet.
However there are various hypotheses mainly based on some initial work done by a number of different teams on how this variant acts once it invades a host, including a number of possible mechanisms at play but they in the main are that this variant has the ability to infect more easily, including that it replicates more readily once in a host. Basically it is more efficient at infecting. So this can mean that smaller viral loads can infect a host. So a transmission setting that may not have resulted in a case in the past, can now do so. A host who may have been less susceptible to the virus, may also be more susceptible to this variant.
As such, whether transmission is aerosol, droplet or fomite is may not matter to it spreading more easily, it is essentially that this variant needs less of a viral load to cause an infection in a host and that makes all three transmission paths more likely to infect.
So that little dose of viral load that may not have breached the body's defenses previously may now do so.
Being more efficient is also why it out competes other strains to become the dominant strain (or at least in communities where the virus in in wide circulation, which in Australia is not the case but in many countries like India and UK it is the case).
"When these viruses mutate, they do so with some advantage to the virus. In this case, it is more transmissible,” CDC Director Dr. Rochelle Walensky
The delta variant has multiple mutations. Scientists don't know the exact function of these mutations at this point in time but they are associated with allowing the virus to bind to the cells of humans and helping the virus to escape some immune responses, said Deepti Gurdasani, a clinical epidemiologist at Queen Mary University of London.
Prof. Wendy Barclay, professor of virology and head of the Department of Infectious Disease at Imperial College London in the U.K., explained that this variant is more transmissible than previous ones because of some key mutations in the spike protein, which allows the virus to penetrate and infect healthy cells.
“The delta variant has got two important mutations in its spike protein, or sets of mutations,” she noted. “One is at the furin cleavage site, which we think is quite important for the fitness of the virus in the airway.”
“The virus that emerged in Wuhan was suboptimal in that respect, so it transmitted but perhaps not as well as it might. The alpha variant took one step towards improving that with a certain mutation, and the delta variant has built on that and taken a second step now, a bigger step, towards improving that feature,” said Prof. Barclay.
Part of scientists’ concern with the Delta variant is that a more transmissible virus can make social distancing less successful.
Tassie will probably lock us out.... I might have to pull a flight forward.
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