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Infectious Diseases

Updated 17 August 2020

Researchers find clues to why Covid-19 affects patients so differently

Covid-19 has affected many people in different ways. New researchers reveal possible reasons why this is the case.

  • New controversial findings reveal that SARS-CoV-2 may not be infecting the lungs as we thought
  • ACE2 receptors, known for playing a role in infection, are present at low levels in lung tissue
  • Ongoing studies are attempting to find out exactly how SARS-Cov-2 infects our cells

As the Covid-19 outbreak unfolds around the world, doctors and researchers are learning more about its devastating impact.

Since the beginning of the outbreak, people have been experiencing Covid-19 in different ways – with some experiencing few or no symptoms, while others succumb to the disease. Research has also revealed signs of significant vascular and neurological damage.

But what exactly makes this virus so complicated? Researchers from McMaster University and the University of Waterloo believe that SARS-CoV-2 is not the respiratory disease we think we know.

Controversial findings

Previous research in March 2020 pinpointed the ACE2 receptor on cell surfaces as the reason why SARS-CoV-2 spreads so easily and is able to impact so much more than the lungs.

But now, research has found that the ACE2 receptor actually doesn't have a strong presence in human lung tissue – which means that the respiratory aspect of Covid-19 is only the tip of the iceberg. The findings of the research have been published in the European Respiratory Journal.

"Our finding is somewhat controversial, as it suggests that there must be other ways, other receptors for the virus, that regulate its infection of the lungs," said Jeremy Hirota, co-lead scientist of the team from the Research Institute of St. Joe's Hamilton and an Assistant Professor of Medicine at McMaster.

"Finding such low levels of ACE2 in lung tissue has important implications for how we think about this virus," stated co-lead Andrew Doxey, Professor of Biology at the University of Waterloo. "ACE2 is not the full story and may be more relevant in other tissues such as the vascular system,” he stated in a news release.

Why does this virus cause different symptoms in different people?

The researchers are exploring the ways SARS-CoV-2 enters the body and causes illness by using nasal swabs to determine which genes are being expressed by patients’ cells. This process forms part of their ongoing study.

"It is clear that some individuals respond better than others to the same SARS-CoV-2 virus. The differential response to the same virus suggests that each individual patient, with their unique characteristics, heavily influences Covid-19 disease severity," stated Hirota, who holds the Canada Research Chair in Respiratory Mucosal Immunology at McMaster, in the news release.

"We think it is the lung immune system that differs between Covid-19 patients, and by understanding which patients' lung immune systems are helpful and which are harmful, we may be able to help physicians proactively manage the most at risk-patients."

READ | Why exactly does the coronavirus spread so easily among people?

READ | The many cardiovascular risks of Covid-19

READ | Research reveals why you shouldn't overlook the gastro symptoms of the new coronavirus 

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