The detection of a mutant strain of SARS-CoV-2 on Australian soil is causing alarm, with the national cabinet announcing new border measures to shield the nation and the population of Brisbane is being placed in a three-day lockdown.
We talk to two leading virologists about what this mutation means, both in terms of its transmissibility and the efficacy of the vaccines.
Their message: yes, it’s serious but certainly not unexpected and certainly not unmanageable.
The mutant strain, which has been causing the UK so much trouble, was detected in a Queensland quarantine hotel cleaner
The strain itself has 17 mutations that researchers say make it up 70% more infectious than other strains.
In other words, these mutations increase the R value, or infectivity rate, of SARS-CoV-2 by between 0.4 and 0.7.
Known as 20B.501Y.V1 or the B.1.1.7 lineage, the strain has previously been detected in international travellers in hotel quarantine in Australia, while a similar strain (20C/501Y.V2 or the B.1.351 lineage) has also been detected in South Africa.
Although there is no evidence that either variant causes more severe illness in those infected, there are concerns that their rapid spread could undo much of the work that has been done to date to manage the pandemic.
“Most of the concern focusses on the spike protein because that’s where vaccines have to work,” Professor Purcell told Australian Doctor.
“We have to produce antibodies that stop [the spike protein] from interacting with receptors on the target cells.”
Professor Purcell described the spike protein as functioning like an arm that can reach out and “grab hold” of these receptors, namely the ACE2 receptor.
“The end of the arm, or the tip of the spike protein, has what we call a receptor-binding domain like a hand that will hold tightly onto the receptor,” he says.
“We also know that when we studied that interaction that it takes much longer for the hand to disengage.”
Together, these changes tip the balance in favour of the coronavirus, he says, which makes it easier to infect target cells such as those that line the nasal passage.
As a result, this means that the antibodies produced in response to infection need to be of higher quality and quantity to overcome these mutations.