Some people have a stronger immune system due to their sex, genetics and previous exposure to pathogens David Garcia/Shutterstock
WE ALL know that person. The one who rarely gets ill. The covid-19 pandemic highlighted that when it comes to catching circulating viruses and bacteria, we aren’t all equal: some people can resist being infected by a pathogen even after heavy exposure. Finding out why could help keep the rest of us in better health.
A person may resist an illness because they have recently been exposed to the pathogen that causes it and their body knows how to fight it off. This wasn’t the case for covid-19, as no one had encountered the coronavirus behind it before the end of 2019. Some people did seem to have some resistance to it, though, due to past infections with other, similar viruses – there are at least four coronaviruses that cause ordinary colds. In 2021, a few healthcare workers who had never tested positive for covid-19 despite heavy exposure were found to have had “abortive infections”, when the virus briefly replicates inside the nose and airway before being wiped out. Their immune systems were found to react to an enzyme used by the virus that causes covid-19 as well as the cold-causing coronaviruses.
People may have resistance to infections because of their genetic make-up. For covid-19, this has been investigated in relation to people’s risk of dying from or needing respiratory support due to their infection. Earlier this year, Johnathan Cooper-Knock at the University of Sheffield, UK, and his colleagues found more than 1300 genetic variants …
