COVID: a never-ending story

continued from Page 35 that “infection with the Omicron variant was less likely to lead to long COVID than the Delta variant,” an observation supported by findings presented to the European Congress of Clinical Microbiology and Infectious Diseases in Copenhagen in April 2023.

The Swiss study, from the Cantonal Hospital St Gallen, found that while 67% of healthcare workers with Delta indicated long COVID symptoms, those first infected with Omicron were no more likely to report symptoms than healthcare workers who had never caught COVID.

Indeed, international and Australian studies published in 2023 have already started to answer some of the big questions posed by the committee – a crucial development given that leading Australian long COVID resources, such as the NSW COVID-19 Critical Intelligence Unit and National Clinical Evidence Taskforce on COVID-19, depend on weekly updates in research to inform doctors and clinical practice.

Complex signs

One of the most comprehensive reviews from 2023, Long COVID: major findings, mechanisms, and recommendations, published 13 January revealed that “hundreds of biomedical findings have been documented, with many patients experiencing dozens of symptoms across multiple organ systems.”

The analysis, led by Professor Eric Topol, Director of Genomics at the US Scripps Research Translational Science Institute, highlighted that common new-onset conditions included cardiovascular, thrombotic and cerebrovascular disease, type 2 diabetes (where risk stayed elevated by 27% for up to 12 weeks), myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and dysautonomia.

“Long COVID is associated with all ages and acute phase disease severities, with the highest percentage of diagnoses between the ages of 36 and 50 years, and most long-COVID cases are in nonhospitalised patients with a mild acute illness,” Professor Topol said.

Significantly, the review showed that the incidence rate was estimated at 10-30% for nonhospitalised cases, 50-70% for hospitalised cases, and 10-12% for vaccinated cases, giving further impetus to the investigation of vaccine-based interventions.

Vaccination was associated with an overall 43% reduction in the risk of developing long COVID, and on Professor Topol highlighted that Paxlovid had just reported a 26% efficacy rate in initial long-COVID tests, with another study about to commence.

The greatest increase in healthcare use was attributable to just 1% of people who developed long COVID.

Solid data on recovery time also emerged from Israel in research published in January in BMJ, which found that people who developed long-COVID after a mild infection took an average of 12 months to recuperate, with most symptoms more prominent during the first six months.

Hair loss, chest pain, cough, muscle aches and pains, and respiratory disorders were usually resolved between six to 12 months, yet infection was “significantly associated with increased risk of loss of smell and taste, concentration, memory impairment, breathing difficulties, weakness, palpitations, streptococcal tonsillitis and dizziness throughout the study.

“The overall burden of conditions after infection across the 12-month study period was highest for weakness (an additional 136 people per 10,000) and breathing difficulties (107 per 10,000),” Dr Maytal Bivas-Benita from the KI Research Institute said.

Vax protection

“Importantly, the risk for lingering dyspnoea was reduced in vaccinated patients with breakthrough infection compared with unvaccinated people, while risks of all other outcomes were comparable.”

Evidence from other investigations also indicated the potential impact of other case severities and paths of infection on prolonging longCOVID’s impact.

“Symptoms can last for years, and particularly in cases of new onset

ME/CFS and dysautonomia are expected to be lifelong,” Professor Topol clarified, and the review noted that the “overwhelming diagnostic similarity” between long-COVID and ME/CFS was highlighted by numerous studies. Australian researchers from Griffith University confirmed this in March using an ultra-high field 7 Tesla MRI to map the physiological similarities between long COVID and ME/CFS. Their study, published in Frontiers in Neuroscience, revealed that the brainstem was significantly larger in ME/CFS and long-COVID patients.

Complications

“We also discovered smaller midbrain volumes were associated with more severe breathing difficulty in ME/CFS and long COVID patients,” lead author Dr Kiran Thapaliya said.

“Brainstem dysfunction in ME/CFS and long-COVID patients could contribute to their neurological, cardiorespiratory symptoms and movement disorder.” https://medicinesaustralia.com.au/code-of-conduct/about-the-code/ https://www.tga.gov.au/legislation-legislative-instruments

In addition to dysfunctional signalling in the brainstem and/ or vagus nerve, 2023 also reinforced findings that longCOVID could be attributed to multiple, overlapping causes, including “immune dysregulation, impacts on microbiota and virome, autoimmunity and priming of the immune system from molecular mimicry, and microvascular blood clotting with endothelial dysfunction.

A key discovery, however, was that “persisting reservoirs” of SARSCoV-2 were identified in different tissues of patients with longCOVID.

Multiple reports following gastrointestinal biopsies also indicated the presence of SARSCoV-2, along with an increased number of cytotoxic T cells.

One of the key themes to emerge was that researchers have consistently warned that governments should prepare for sustained healthcare demand thanks to the global impact of long-COVID.

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