Why do some healthy, vaccinated people take so long to recover from Covid-19 infections, while others – perhaps older or even less healthy – just shrug the virus off?
Experts from Singapore say that the answer is often in our genes.
Each person is unique and can have a different reaction to the virus.
Professor Laurent Renia, from the Nanyang Technological University’s Lee Kong Chian School of Medicine, puts it succinctly: “We are not born equal.”
One example is how the human body produces proteins known as interferons, which help mount a defence against viruses.
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But in some people, there are errors in the molecular circuitry involved in generating such proteins, which can make them more susceptible to infection, Prof Renia said.
An international study revealed that 3.5 percent of patients with severe Covid-19 disease had such mutations.
Scientists subsequently discovered that at least 15 per cent of such patients had another problem – “misguided” antibodies that attacked interferons and prevented them from doing their job.
Prof Renia stated that these are just a few of the possible genetic factors at play. He added that many others are still being discovered.
“Identifying these patients with deleterious mutations may help tailor specific treatment for them,” he added.
Even within the same family, immune systems can differ greatly, said Associate Professor Ashley St John from Duke-NUS Medical School’s Emerging Infectious Diseases Programme.
This is because of the unique combination of genes that work together to fight infection, as well as each individual’s previous exposure to vaccines or other infections.
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The amount of virus that a person is exposed to can also impact how ill they become, she added.
Although there are conflicting data, it is generally believed that people who are exposed for longer periods of time to the virus can get sicker.
And subtle behaviour differences could also explain why some people fall sick and show symptoms, but others do not, even if it seems they both had the same exposure to an infected person, Prof St John said.
These minor differences could include where the person was sitting relative to the infected individual or if the mask was correctly worn at that time.
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Prof St John added that vaccination is one of the most important factors impacting how ill a person becomes.
“There are very few aspects involved in the process of developing symptomatic disease or severe disease that we can control, but the best strategy, which we have control over, is to be fully vaccinated.”
This article was published in The Straits Times for the first time.
Source: Her World