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Coronastream: long COVID, waves around the world and genetic predisposition to pneumonia

Posted on October 27, 2020 by Dr Tim Inglis

In this special blog series, medical microbiologists led by Dr Tim Inglis summarise some of the research that will be essential to inform COVID-19 countermeasures. Find out more about the project in Dr Inglis' Editorial 'Logic in the time of coronavirus', published in the Journal of Medical Microbiology.

By now, we're all thinking that the pandemic has to run out of steam at some point. But, as we head towards the end of the year, SARS-CoV-2 just keeps on coming. Whether you're suffering the long-term consequences of COVID-19 infection that refuse to budge, or you're a number cruncher risking another look at the epidemic curve; it just keeps on going on. And against expectations, some of the places with the most rudimentary public health have managed to keep a lid on things, while wealthier nations have seen the virus spread widely and travel all the way to the top. At least the science is beginning to make sense, as reflected in the recently published literature.

Not yet the endnote: If you've paused at this half year-into-the-pandemic mark to look over the horizon, there's a link below to a thought-provoking essay that will give you a new perspective on the malign intelligence behind our SARS-CoV-2 adversary.

Congruence: clinico-pathological features

Long COVID: How to define it and how to manage it

This account of a British Medical Journal (BMJ) webinar summarises an expert panel discussion on the emerging syndrome of persisting clinical features that persist after the initial SARS-CoV-2 infection. The prevalence of long COVID is probably underestimated and its impact may not be fully appreciated for some time. The wide range of symptoms that may last for weeks to months after the acute infection, makes it difficult to arrive at a clear definition of long COVID. One suggested is "not recovering [for] several weeks or months following the start of symptoms that were suggestive of COVID, whether you were tested or not.” Profound fatigue is recognised as one of the most common symptoms in long COVID. Post-viral cardiomyopathy also occurs with relatively high frequency. While many patients appear to recover slowly, specialist referral is recommended for the small proportion who do not.

Consistency: epidemiology

COVID-19: A global and continental overview of the second wave and its (relatively) attenuated case fatality ratio

This analysis of publicly available data on cases and deaths between December 2019 and September 2020 reveals three distinct pandemic periods in which there were an initial peak, a plateau and a second peak. There are distinctive patterns at a continental level, particularly in the third period, with Europe increasing again, and the Americas and Africa declining. There is a reduced case-fatality ratio in the global second wave of COVID.

Cumulative dissonance: pathophysiology

Inborn errors of type I IFN immunity in patients with life-threatening COVID-19

In this study of 659 patients with life-threatening COVID-19 pneumonia and 534 with asymptomatic or benign infection, this group were able to define loss of function variants in 23 patients. They conclude that inborn errors of TLR3 and IRF7 dependent type I IFN immunity can underlie life-threatening COVID-19 pneumonia. This paper presents a series of experiments that map out cell and molecular processes underlying susceptibility to severe COVID-19 pneumonia. These results suggest that at least 23 of the 659 patients with severe pneumonia had known or new genetic defects in type I IFN induction and amplification.

Curtailment: therapeutic and preventive countermeasures

The potential impact of zinc supplementation on COVID-19 pathogenesis

Zinc was among the cocktail of therapeutic agents given to the current occupant of the White House while under treatment for COVID-19. News media highlighted that there was no published evidence for its effect, but this paper reviews the evidence for a potential benefit from zinc supplementation. Most of the risk groups for COVID-19 are associated with zinc deficiency. Zinc is required for prevention of pathogen entry since it helps preserve epithelial barriers, aspects of immune and metabolic function, and may contribute to the development of around 16% deep respiratory infections globally. Interestingly, ACE-2 is a zinc-metalloenzyme. Zinc also directly affects viral replication, and has several stabilising effects on immune function. While direct evidence for a clinical benefit of preventive or therapeutic zinc is lacking, there is published support for its benefit in viral respiratory infections. At present, zinc supplements appear to be a low risk/high benefit approach.