Coronavirus science | Week in review: 'Long Covid', second 'key' and attacked by the immune system



READ | Researchers discover a second 'key' that makes the new coronavirus infectious

As the number of confirmed global SARS-CoV-2 infections nears 44 million, scientists are still battling to understand what makes the virus so effective and transmissive.

But a new study may have the answer: The virus is using a second protein, called neuropilin-1, to facilitate entry into human cells.

The first receptor, angiotensin-converting enzyme 2 (ACE2), was discovered during the early stages of the pandemic, and scientists came to understand how the virus used it to bind to the surface of cells. An enzyme called type II transmembrane serine protease (TMPRSS2) was also found to be crucial for gaining entry.

The findings of the researchers, from the Technical University of Munich in Germany and the University of Helsinki in Finland, were published in Science.

"To efficiently infect human cells, SARS-CoV-2, the virus that causes Covid-19, is able to use a receptor called neuropilin-1, which is very abundant in many human tissues, including the respiratory tract, blood vessels and neurons," a news release by the University of Helsinki stated.

"The starting point of our study was the question why SARS-CoV, a coronavirus that led to a much smaller outbreak in 2003, and SARS-CoV-2, spread in such a different way even if they use the same main receptor ACE2," said University of Helsinki virologist Ravi Ojha.

READ | 'Long Covid': These factors may reveal whether you’ll suffer long term

One in 20 people infected with Covid-19 is estimated to remain sick for at least eight weeks, a new study suggests.

Known by the unofficial medical term "long Covid" (also known as "long haul"), it involves cases in which patients suffer from symptoms of the illness for longer than the official World Health Organisation-endorsed two-week period.

Researchers from King's College London (KCL), whose study was published in medRxiv and is still awaiting peer review, analysed more than 4 000 Covid-19 patients across Sweden, the UK, and the US. They were asked to record their symptoms in a Covid Symptom Study app.

They found that older people, women, and those who experienced more than five symptoms during their first week of illness were more likely to develop long Covid.

The following five symptoms were identified as predictors of long Covid: fatigue, headache, difficulty breathing, a hoarse voice, and muscle or body aches.

These findings could serve as a warning and identify Covid-19 patients who need extra care.

READ | Coronavirus: Symptomatic children carry more virus than those without symptoms, study suggests

Children who test positive for the new coronavirus, but are asymptomatic (don't display symptoms) have significantly lower levels of the virus compared to those who experience symptoms.

This was according to a new study based on an analysis of 817 children from nine hospitals in the US and Canada who tested positive for SARS-CoV-2.

The findings were published in the Journal of Clinical Microbiology.

Although the study was the first large and comprehensive analysis of SARS-CoV-2 viral loads in asymptomatic children, the authors cautioned that the reason behind their finding was still unclear and required further research.

"While these findings provide some reassurance about the safety of asymptomatically infected children attending school, these unanswered questions suggest that risk mitigation measures in daycares, schools and the community remain critical to reduce the spread of Covid-19," said lead author and epidemiologist, Larry Kociolek of the Northwestern University in Illinois.

The study included 339 asymptomatic and 478 symptomatic children (ages 0–17 years). All children in the study tested positive for the virus through polymerase chain reaction (PCR) tests.

Asymptomatic children who had either diabetes or recently had contact with a known Covid-19 case were more likely to have high viral loads.

READ | Some Covid-19 patients are attacked by their own immune systems – a new study explains why

Some people are at greater risk of severe Covid-19, the disease caused by SARS-CoV-2. According to a recent study, autoreactive antibody production may explain why this happens.

The study, which was published in preprint server medRxiv, while awaiting peer-review, explains that instead of targeting disease-causing microbes, these immune proteins, called autoantibodies, target the tissues of patients suffering from severe Covid-19.

The researchers explained that their findings have a potential impact on both acute patient care and infection recovery.

Harvard Health explains that autoantibodies attack several different parts of the body, resulting in inflammation and tissue damage in the joints, skin, kidney, nervous system (brain and spinal cord), blood, and heart, among others.

More than this, they can also attach themselves to body chemicals and form abnormal molecules (known as “immune complexes”) that trigger additional inflammation when they are deposited in the body’s organs and tissues.

Previous studies during the earlier stages of the pandemic found that abnormal blood clotting in Covid-19 patients is more likely to lead to complications and admissions to the intensive care unit (ICU).

READ | Dementia and other cognitive disorders linked to severe Covid-19, study suggests

New research from the University of Georgia suggests that cognitive disorders, including dementia, may be risk factors for developing severe Covid-19, the disease caused by the new coronavirus.

The study, conducted by a team of researchers from the University of Georgia, was published in the journal Brain, Behavior, and Immunity.

The researchers used data from the UK Biobank, involving over 500 000 participants. The data of the participants with Covid-19 started being gathered in March this year, at the beginning of the pandemic in the US.

According to the researchers, their findings stress the need for special care for people with preexisting cognitive disorders during the pandemic.

In their study, the team analysed data from an extensive list of 974 medical conditions and 30 blood biomarkers, and their association with Covid-19.

Additionally, they also tested the association of genetic variants in two key genes related to SARS-CoV-2 infection – angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) – with Covid-19 or any other phenotypes.


SA cases update: 

The latest number of confirmed cases is 726 823.

According to the latest update, 19 411 deaths have been recorded in the country.

There have been 655 330 recoveries.

So far, more than more than 4.84 million tests have been conducted, with 19 543 new tests reported.

Global cases update:

For the latest global data, follow this interactive map from Johns Hopkins University & Medicine.

Late on Sunday night, positive cases worldwide were more than 46.36 million, while deaths were more than 1.19 million.

The United States had the most cases in the world - more than 9.17 million, as well as the most deaths - more than 230 000.


Latest news:

HEALTH TIPS (as recommended by the NICD and WHO)

• Maintain physical distancing – stay at least one metre away from somebody who is coughing or sneezing

• Practise frequent hand-washing, especially after direct contact with ill people or their environment

• Avoid touching your eyes, nose and mouth, as your hands touch many surfaces and could potentially transfer the virus

• Practise respiratory hygiene – cover your mouth with your bent elbow or tissue when you cough or sneeze. Remember to dispose the tissue immediately after use.

Image credit: Getty Images

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