Posted by John Mooney FFPH, Consultant in Public Health, NHS Grampian @StandupforPHlth
Watch 'Sound of Sirens' by John Mooney and Dr Clare Pettinger (AKA the Singing Dietitian) inspired by this blog post
This is now my third Fuse blog about Covid, in what is sadly proving to be a rather prescient series of posts about the pandemic. I set out in the first (published in February 2020), that as a newly emergent single stranded RNA virus, Covid-19 would be genetically unstable and undergo mutations which could influence its epidemiological characteristics including virulence and transmissibility. To say therefore that the present situation was not foreseeable (given my rudimentary grasp of evolutionary genetics), is clearly not that convincing. It’s probably even more self-evident that the more transmissible variants will be the same variants that are most transmitted, because this is the essence of viral survival strategy. Even with that knowledge however, the speed with which the Delta variant became the dominant strain (from under 10% to over 90% in a matter of weeks and now accounting for 99% of identified cases), was fairly breath-taking even by viral standards.
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A particular concern just now of course must be that the UK’s success in achieving a high vaccination uptake creates a new ‘selection pressure’ of its own, in that any newly emergent strain with the capacity to evade vaccine induced immunity will have an enormous selection ‘advantage’ in a population which has the combined characteristics of a high vaccination rate plus a high level of circulating virus. It’s easy to appreciate then how such a new variant could assume a ‘delta-style’ trajectory towards dominance, leaving even the fully vaccinated vulnerable once more. This is of course not a reason for reducing vaccination efforts which have been critical in protecting vaccinated age groups, thereby reducing the proportion of the population susceptible to new infections. If I could squeeze in one final take-home vaccine basics key message: the more infectious a particular variant, the higher proportion of a population needs to be vaccinated to mitigate transmission. This has prompted some commentators to expect that the holy grail of ‘herd immunity’ will always prove elusive for Covid.
The very real challenge for those of us in practice settings (having recently returned to NHS public health myself), is how best to advise local populations and relevant agencies in order to keep reducing the levels of circulating virus. The mechanisms that work here are very much those that are already in place combined with ongoing vaccination and access to local testing. The extent to which people might be willing to submit to testing that could sacrifice a long-coveted holiday, versus their readiness to isolate away from work, might begin to explain a divergence in the surveillance data in some health-board areas between declining numbers of cases and relatively stable hospital admissions (even allowing for the two week lag). The latter of which has already led to cancelled elective procedures in ours and other regions. We also know that infections in younger age groups are more likely to be mild / asymptomatic taking away the ‘illness prompting’ rationale for seeking a test.
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6 months after initial Covid symptoms (mask displaced to drink) |
At this point it would be useful to highlight the relevance of the second blog in this series as then it all looks impressively planned! (Spoiler alert: it wasn’t!). In that article, I described my experience with Long-covid which I was unfortunate enough to develop very early in the first wave and which included an unscheduled hospital stay and fast track angiogram (think X-ray to check heart blood vessels) thanks to a “dangerous ECG”. Thankfully 18 months on I am much recovered, but remain very conscious that there was more than one false dawn over the course of the illness, although later episodes were milder. The inescapable parallel from a population standpoint is that Covid-19 can prove a truly mercurial adversary, lulling you into a sense of comfort and security, just like the mythological Sirens, before dashing you against the rocks of reality once again. The attached illustration above: ‘Ulysses and the Sirens’ is an 1891 painting by Pre-Raphaelite artist John William Waterhouse. In the words of the Wikipedia description:
"The work depicts a scene from the ancient Greek epic the Odyssey, in which the Sirens attempt to use their enchanting song to lure the titular hero Odysseus and his crew towards deadly waters. As per the Odyssey, Odysseus' crew had already blocked their ears to protect themselves from the Sirens' singing, but Odysseus, wanting to hear the Sirens, had ordered his crew to tie him to the mast so that he may have the pleasure of listening without risking himself or his ship."
In other words, the measures clearly employed were distancing and personal protective equipment! [Note the bound ears of the crew]. Perhaps the fact that the new variants are being ascribed Greek lettering might help persuade us to take a leaf from these mythological mariners and maintain some of our protective measures just a little longer while vaccine roll-out continues. In keeping with worrying reports from our clinical colleagues and as anecdotal as this could certainly be described, I have increasingly of late been hearing much more of the sound of sirens…
John is currently employed as a consultant in public health with NHS Grampian and has a background in respiratory infectious disease epidemiology.
1. John William Waterhouse, Public domain, via Wikimedia Commons
The views expressed in posts are those of the authors and do not necessarily reflect those of Fuse (the Centre for Translational Research in Public Health) or the author's employer or organisation.
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