Does anyone else feel that we have entered a “pseudo-war” phase of the Covid-19 pandemic? On the one hand we have the reassurance of high vaccine uptake; on the other, the Delta variant is proving rather adept at breaking through our current range of vaccines – albeit to produce relatively mild infection and lower death rates.
Undoubtedly, the joker in the pack is future variants of concern. These may already be named as variants of interest, but with the potential to become variants of concern.
Variants of interest have features that may reduce our immune system’s ability to prevent infection. Variants of concern are typically less responsive to treatments or vaccines and they tend to be more transmissible and contagious. As yet unidentified variants could make the most of the opportunity of a fertile breeding ground of global infection to produce more infectious and potentially vaccine-resistant versions of Sars-CoV-2.
As an infected cell builds new coronaviruses, it occasionally makes tiny copying errors called mutations. Scientists can track mutations as they are passed down through a lineage, which is a branch of the viral family tree. A group of coronaviruses that share the same inherited set of distinctive mutations is called a variant. Viruses produce variants all the time. A big question is whether future Sars-CoV-2 variants will lengthen the pandemic or make vaccines less effective?
The World Health Organisation (WHO) is highly sensitive to any naming system that is based on a location where the variant was first identified. It has therefore decided to label variants of Sars-CoV-2 using names of Greek alphabet letters: alpha, beta, gamma, and so on. It reckons they will be easier to remember and more practical to use.
However, I’m not sure whether I agree with the WHO statement that “the Greek alphabet is well established as being generic, as the names of its individual letters have already been used for a multitude of purposes”. I certainly cannot rattle off the names of all 24 letters of the Greek alphabet. (In fact, you could say – tongue in cheek – that some of us wouldn’t have an iota where to start.)
A future Covid variant that evades current vaccines could set the battle against the pandemic back by a year or more
But the die is cast and we now routinely refer to Alpha and Delta variants of concern, with Eta, Iota, Kappa and Lambda already identified as Sars-CoV-2 variants of interest.
Delta is the variant of most concern to virologists just now. The viral load of those infected with Delta – meaning the amount of virus detected from the nasal passages of an infected person – is reported to be more than 1,000 times higher than in those infected with the original form of Sars-CoV-2. Viral loads of this magnitude contribute to the especially contagious nature of the Delta variant.
How concerned should we be about future variants of Sars-CoV-2? The UK government’s Scientific Advisory Group for Emergencies has concluded that the arrival of a variant that evades vaccines is a “realistic possibility”. A future Covid variant that evades current vaccines could set the battle against the pandemic back by a year or more, the group has advised.
The most recent variant to ring alarm bells is B.1.621, yet to receive a Greek moniker. The variant – first identified in Colombia – killed seven previously vaccinated older residents in a nursing home in Zavantem, Belgium. Public health experts in England say B.1.621 has shown signs of evading the immune response triggered by either Covid-19 vaccines or previous infection.
Could a future variant force us back into lockdown? It is unlikely as long as current vaccines offer us some protection. Add in a redefinition of Covid as a recurrent infection requiring yearly jabs, alongside a societal determination to live our lives “around” rather than “under” coronavirus, and we can avoid a winter like the last one.
But all bets are off should a future mutation completely evade our vaccine-primed immune systems.
mhouston@irishtimes.com