We all know a few of those lucky people who somehow managed to avoid contracting COVID. Maybe you are one of them. Is this a Marvel-esque superpower? Is there any scientific reason for human resistance to infection with the virus everywhere? Or is it just luck?
More than 60% of people in the UK have tested positive for COVID at least once. However, the number of people who have already been infected with SARS-CoV-2, the virus that causes COVID-19, is believed to be higher. The calculated rate of asymptomatic infection varies depending on the study, although most agree that it is fairly common.
But even considering people who had COVID and didn’t realize it, there’s still likely a group of people who haven’t had it before. Why some people seem immune to COVID is one of the questions that has persisted throughout the pandemic. As with much in science, there is no one simple answer (yet).
Perhaps we can dismiss the Marvel-esque superpower theory. But science and luck likely play a role. lets take alook.
The simplest explanation is that these people have never come into contact with the virus.
This could certainly be the case for people who have been protected during the pandemic. People at a higher risk of developing serious illness, such as those with chronic heart or lung disease, have tough years.
Many of them continue to take precautions to avoid potential exposure to the virus. Even with the extra safety measures, many of these people ended up with COVID.
Due to the high level of transmission in the community, especially with highly transmissible omicron variants, it is unlikely that someone would go to work or school, socialize and shop who was not close to someone infected with the virus. However, there are people who have experienced high levels of exposure, such as hospital workers or family members of people who have contracted COVID, who have somehow managed to avoid positive tests.
We know from many studies that vaccines not only reduce the risk of serious illness, but can nearly halve the chance of transmission of SARS-CoV-2. So, of course, vaccination could have helped some close contacts avoid infection. However, it is important to note that these studies were conducted prior to the omicron. Our data on the effect of vaccination on omicron transmission are still limited.
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One theory as to why some people avoid infection is that despite being exposed to the virus, it fails to create infection even after entering the airways. This may be due to a lack of receptors needed for SARS-CoV-2 to reach cells.
Once a person has been infected, researchers have determined that differences in the immune response to SARS-CoV-2 play a role in determining the severity of symptoms. A rapid and strong immune response can prevent the virus from multiplying to any significant degree in the first place.
The effectiveness of our immune response to infection is largely determined by our age and genetics. However, a healthy lifestyle definitely helps. For example, we know that a lack of vitamin D can increase the risk of certain infections. Not getting enough sleep can have a detrimental effect on our bodies’ ability to fight off invading pathogens.
Scientists studying the underlying causes of severe COVID have identified a genetic cause in nearly 20% of critical cases. Just as genes can be a determinant of disease severity, our genetic makeup may also hold the key to resistance to SARS-CoV-2 infection.
I am looking for SARS-CoV-2 infection on nasal cells from human donors. We grow these cells on plastic dishes to which we can then add the virus and check how the cells respond. During our research we found one donor whose cells could not be infected with SARS-CoV-2.
We discovered some really interesting genetic mutations, including several associated with the body’s immune response to infection, that could explain why. It has previously been shown that the mutation we identified in a virus-associated sensing gene confers resistance to HIV infection. Our research is being conducted on a small number of donors and highlights that we are still only surface research into genetic susceptibility or resistance to infection.
There is also a possibility that previous infection with other types of coronaviruses may lead to reactive immunity. This is where our immune system may recognize SARS-CoV-2 as similar to a newly invaded virus and trigger an immune response. There are seven coronaviruses that infect humans: four that cause the common cold, and one that causes SARS (Severe Acute Respiratory Syndrome), MERS (Middle East Respiratory Syndrome) and COVID.
How long this immunity might be is another question. Seasonal coronaviruses that circulated before 2020 were able to re-infect the same people 12 months later.
Read more: The common cold may protect you from the Corona virus – here’s how
If you’ve avoided COVID so far, you may have a natural immunity to SARS-CoV-2 infection, or you may have just gotten lucky. Either way, it makes sense to continue taking precautions against this virus that we still know so little about.