Why can two young and healthy individuals be affected so differently by coronavirus?


New information about the new coronavirus (SARS-CoV-2) is constantly emerging, which is critical in the race to develop a vaccine and treatment for Covid-19. In a recent discovery, scientists found that a patient’s genes may provide clarity on why one young, healthy individual can be almost unaffected by the virus, while another can become seriously ill and end up in the intensive care unit (ICU).

In looking for rare, ‘silent’ (hidden) gene mutations that are triggered by the virus, researchers are hoping it will take them one step closer to potential treatments.

At risk: Not just older people with underlying illnesses 

It’s agreed that the Covid-19 virus causes severe disease and kills older people with chronic illness; those with underlying medical conditions such as diabetes and lung disease; and men, at a greater rate than young people.

However, in an unexpected twist, we’re seeing a minority of patients who are under 50 take up space in ICUs around the world as well – without any underlying medical conditions.

Speaking to AFP, and quoted in a ScienceAlert article, geneticist Jean-Laurent Casanova – director of the human genetics of infectious diseases laboratory jointly based at the Imagine Institute in Paris and Rockefeller University in New York – revealed that this amounts to roughly five percent of patients: "Someone who could have run the marathon in October 2019, and yet in April 2020 is in intensive care, intubated and ventilated."

Casanova’s goal is to find out if these patients may possibly have rare genetic mutations. "The assumption is that these patients have genetic variations that are silent until the virus is encountered," he explained.

The geneticist also co-founded the Covid Human Genetics Effort, which will analyse the genome of younger Covid-19 patients with severe illness in China and Europe, and also hopes to find out why certain people do not become infected, in spite of repeated exposure.

Earlier this month, HealthDay reported on this international study, led by Casanova. It will enrol 500 patients under the age of 50 with no underlying health conditions, and who have been diagnosed with Covid-19 and admitted to ICU.

Gene mutations can also offer protection

Gene mutations may be given a bad rap for making certain people more susceptible to a number of viral infectious diseases, such as influenza, but there is also a positive side.  

According to ScienceAlert, researchers found a particularly rare mutation of a single gene, named CCR5, in the 1990s. This mutation actually offered protection against disease in that it stopped people from contracting HIV, laying the foundation for the development of treatments.

How may this help in Covid-19 treatment?

Mark Daly, director of the Institute for Molecular Medicine Finland, told AFP that with a “very large sample and collaboration, and the ability to repeat the observation to be confident about the results”, as well as recruitment of at least 10 000 patients, their project will hopefully help to develop a treatment.

"There are a huge number of medicines available that target specific genes. If we find a genetic clue that points us to a gene that already has a medication developed, then we could simply repurpose the drug," he said. However, in the event that mutations in genes are found and there aren’t currently medications available for them, it might make the process more complex.

On 12 May, the virus has infected more than 4.1 million people and killed over 286 000 worldwide, according to a report by the Johns Hopkins Coronavirus Resource Centre.

READ | Coronavirus in SA: All the confirmed cases

READ | Coronavirus crisis has fewer kids getting needed vaccines

READ | Low vitamin D levels and Covid-19 - what researchers found

Image: Getty Images

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