News: A look at the factors that may determine the severity of infection-24/06/2020
Updated On: Jun 24, 2020
A look at the factors that may determine the severity of infection
Small Medium Large A look at the factors that may determine the severity of infection Across continents and demographics, the novel coronavirus is not a uniform phenomenon. Some have suffered from severe forms of Covid-19 while others appear to have been spared. While old age and pre-existing conditions are known to exacerbate the effects of the viral infection, scientists are broadening their search to better understand why some people face greater risks from Covid-19 than others. HOW AND HOW MUCH YOU GET EXPOSED MATTERS The manner in which one gets infected could play a role in deciding the severity of the infection. Some scientists say “aerosol transmission”, which is when the virus spreads through very fine droplets that can hang in the air for longer than particles expelled while sneezing, coughing or talking, may be more dangerous. While the body has mechanisms to block larger foreign particles, these small aerosol droplets can reach deeper into the lungs, where the virus takes a much stronger hold than in other parts of the lungs. Sneeze guards installed at an office in California (NYT Photo) read caption Sneeze guards installed at an office in California (NYT Photo) Another factor is the amount of the virus transmitted, or viral load. Exposure to larger quantities of the coronavirus at the time of infection can result in more severe illness. This could explain why some frontline healthcare workers have experienced more serious forms of Covid-19 despite not bearing any other major risk factors. The potential impact of larger viral loads also places prominence on the need for proper social distancing — you’ll be exposed to less of the virus the further you are from the source. Once it enters the body, the coronavirus invades cells through ACE2 receptors on the surfaces of lung cells, blood vessels, intestines and in the back of the throat and nasal passage. Some studies say children could face a lower risk of infection because they have fewer ACE2 receptors, a protein on the surface on many cell types to which viruses stick easily. Read TOI without Ads Unlock ad-free experience and exclusive benefits from 20+ brands Learn More No credit card required START FREE TRIAL Also, earn +100 TimesPoints 6/27/2020 Why Covid-19 hits some harder than others - Times of India https://timesofindia.indiatimes.com/india/why-covid-19-hits-some-harder-than-others/articleshow/76544521.cms 3/15 Children could face a lower risk of infection because they have fewer ACE2 receptors, according to some studies read caption Children could face a lower risk of infection because they have fewer ACE2 receptors, according to some studies SCIENTISTS ARE LOOKING FOR CLUES IN BLOOD Blood could hold the key to understanding why some Covid-19 patients are worse affected than others. A European study found that the ABO gene, which determines blood type, could help explain respiratory failure in Covid-19 patients. Those with blood type A had a 50% higher chance of needing oxygen or a ventilator while those with type O appeared to experience a less severe bout of infection. Patients with type A blood also developed small blood clots, which is a more severe symptom of the virus. Though it’s still unclear what role the gene plays, one expert suggested it might be linked to inflammation caused when the immune system fights off a pathogen. Researchers in China have also developed an artificial intelligence tool that analysed blood and identified 22 proteins that were common in blood samples from patients with severe forms of Covid-19. Though yet to be used on a large scale, it’s the type of test that could help identify the most vulnerable patients early on. Those with blood type A had 50% higher chance of needing oxygen or a ventilator than those with type O, according to a European study read caption Those with blood type A had 50% higher chance of needing oxygen or a ventilator than those with type O, according to a European study Scientists are increasingly searching for answers in genes, too. An international coalition of researchers is trying to pinpoint the genetic variants that are common among outlier cases, such as severely ill patients under 40 with no pre-existing conditions. There’s early evidence that certain genetic mutations in people can make them more susceptible to infectious diseases like influenza. AGE AND COMORBIDITIES It’s now been known for a while that people with pre-existing conditions — like heart disease, diabetes and obesity — are more susceptible to the coronavirus. Researchers say understanding how specific comorbidities affect Covid-19 patients could improve the treatment for certain risk groups and help in reopening economies. For instance, an epidemiologist found that obesity was the biggest risk factor among patients aged below 60 in one US hospital. Patients with a body mass index of 30 to 34, defined as obese by the US Centers for Disease and Control, were twice as likely to be admitted to the ICU than those with a BMI under 30. And those with a BMI above 35 were three times more likely to die. Not only are older people more likely to have more pre-existing conditions, they also tend to suffer from immunosenescence — a weakening of the immune system with age. 6/27/2020 Why Covid-19 hits some harder than others - Times of India https://timesofindia.indiatimes.com/india/why-covid-19-hits-some-harder-than-others/articleshow/76544521.cms 4/15 Senior citizens tend to suffer from immunosenescence — a weakening of the immune system with age read caption Senior citizens tend to suffer from immunosenescence — a weakening of the immune system with age THE IMMUNE SYSTEM CAN BACKFIRE Some people have immune systems better equipped to tackle diseases than others. While the immune system has several mechanisms to fight off an infection, sometimes it can backfire too. In the event of an illness, the body produces cytokines, which help direct the immune system response. Cytokines are small proteins released by many different cells in the body, including those of the immune system where they coordinate the body's response against infection and trigger inflammation. If there aren’t enough cytokines, the immune response won’t be strong enough to beat the disease. But if the body generates too many cytokines, it can lead to an overreaction of the immune system — called a cytokine storm — in which the immune system attacks the body itself, leading to death in some cases.
