COVID-19

WHO has working definitions for SARS-CoV-2 Variant of Interest (VOI) and Variant of Concern (VOC).

A SARS-CoV-2 VOI is a SARS-CoV-2 variant with genetic changes that are predicted or known to affect virus characteristics such as transmissibility, disease severity, immune escape, diagnostic or therapeutic escape; and that has been identified as causing significant community transmission or multiple COVID-19 clusters, in multiple countries with increasing relative prevalence alongside increasing number of cases over time, or other apparent epidemiological impacts to suggest an emerging risk to global public health.

A SARS-CoV-2 VOC is a SARS-CoV-2 variant that meets the definition of a VOI (see above) and, through a comparative assessment, has been demonstrated to be associated with one or more of the following changes at a degree of global public health significance, increase in transmissibility or detrimental change in COVID-19 epidemiology; OR increase in virulence or change in clinical disease presentation; OR decrease in effectiveness of public health and social measures or available diagnostics, vaccines, therapeutics.

Source: WHO

WHO designated the variant B.1.1.529 a variant of concern, named Omicron, on the advice of WHO’s Technical Advisory Group on Virus Evolution (TAG-VE). It is not yet clear whether Omicron is more transmissible compared to other variants, including Delta. The number of people testing positive has risen in areas of South Africa affected by this variant, but epidemiologic studies are underway. It is not yet clear whether infection with Omicron causes more severe disease compared to infections with other variants, including Delta. Preliminary data suggests that there are increasing rates of hospitalization in South Africa, but this may be due to increasing overall numbers of people becoming infected, rather than a result of specific infection with Omicron. there may be an increased risk of reinfection with Omicron as compared to other variants of concern, but information is limited. The widely used PCR tests continue to detect infection, including infection with Omicron, as we have seen with other variants as well.

Source: WHO

The persistent breathing issues that plague some COVID-19 survivors, known as ‘long COVID,’ may be due to microscopic processes that continue to damage lungs even after the acute infection is over, new findings suggest. Researchers studied blood and bronchoalveolar fluid samples from 38 patients who still had breathing problems at least three months after they were discharged from hospital.

Source: Medrxiv.org

Internal Centers for Disease Control and Prevention (CDC) documents support the high transmission rate of the delta variant and put the risk in easier to understand terms. The documents also show that breakthrough infections in the vaccinated make people about as contagious as those who are unvaccinated. In addition to being more transmissible, the delta variant likely causes more severe COVID-19 illness.

Source: Medscape

Nerve fiber loss and an increase in dendritic or key immune cells on the cornea may help identify Long COVID, according to a small study published online today in the British Journal of Ophthalmology.

Long COVID is characterised by a range of potentially debilitating symptoms which develop in at least 10% of people who have recovered from acute SARS-CoV-2 infection. This study has quantified corneal sub-basal nerve plexus morphology and dendritic cell (DC) density in patients with and without long COVID.

Corneal confocal microscopy identifies corneal small nerve fibre loss and increased DCs in patients with long COVID, especially those with neurological symptoms. CCM could be used to objectively identify patients with long COVID.

Source: British Journal of Ophthalmology

Treating critically ill COVID-19 patients with arthritis drugs tocilizumab and sarilumab significantly improves survival rates and reduces the amount of time patients need intensive care.

The immunosuppressive drugs, Actemra, also known as tocilizumab, and Kevzara, also known as sarilumab, reduced death rates by 8.5 percentage points among patients hospitalised and severely ill with the pandemic disease.

Among hospitalised Covid patients, administering one of the drugs in addition to corticosteroids reduced the risk of death by 17 percent, compared to the use of corticosteroids alone.

In patients who were not on ventilators, the risk of progressing to mechanical ventilation or death was reduced by 21 percent, compared to the use of corticosteroids alone.

Severely ill COVID patients experience an immune system overreaction known as a “cytokine storm” that can cause severe organ damage and death.

Tocilizumab and sarilumab are used to treat rheumatoid arthritis, an autoimmune condition, by inhibiting the effects of interleukin (IL)-6, a type of protein called a cytokine that signals the body to mount an inflammatory response.

But previous research on whether IL-6 inhibitors can be useful against severe COVID have variously reported benefit, no effect, and harm.

This prompted the WHO to coordinate the new study that combined data from 27 randomized trials conducted across 28 countries.

Source: Journal of the American Medical Association

Sofosbuvir/ledipasvir and nitazoxanide both appeared to clear SARS-CoV-2, the virus that causes COVID-19 in a preliminary trial, said Mohamed Medhat, lecturer in the department of gastroenterology and tropical medicine at Assiut University Hospitals in Assiut, Egypt.

SARS-CoV-2 shares similarities to the hepatitis C virus in the way it replicates, Medhat said. Molecular docking studies, which use computation to find ligands that bind to proteins, suggested that both sofosbuvir/ledipasvir and nitazoxanide might block key proteins in SARS-CoV-2.