Do you know someone that has been fortunate enough to go the whole two years that we've spent in the pandemic without contracting the coronavirus? Well, it turns out this is just one of many mysteries brought on by the pandemic and being investigated by infectious disease specialists. So why do some people seem to not be affected by COVID at all? Here's what we know so far.
You may think that being in the same space as someone who tested positive for COVID automatically means you will catch it, but Danny Altmann, professor of immunology at Imperial College London, tells CNBC that studies indicate the likelihood of becoming infected within a household once one case is positive is “not as high as you’d imagine.”
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"Never COVID"
Currently, researchers are trying to put a finger on exactly why some people seem to be immune from catching COVID, a term they are coining "never COVID".
According to CNBC, new research was published last month by Imperial College London which suggests that people with higher levels of T cells (a type of cell in the immune system) from common cold coronaviruses were less likely to become infected with SARS-CoV-2, the virus that causes COVID-19.
Dr. Rhia Kundu, first author of the study from Imperial’s National Heart and Lung Institute, says that “being exposed to the SARS-CoV-2 virus doesn’t always result in infection, and we’ve been keen to understand why.”
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“We found that high levels of pre-existing T cells, created by the body when infected with other human coronaviruses like the common cold, can protect against COVID-19 infection,” she adds.
However, Kundu warns people against considering this a method of protection.
“While this is an important discovery, it is only one form of protection, and I would stress that no one should rely on this alone. Instead, the best way to protect yourself against COVID-19 is to be fully vaccinated, including getting your booster dose,” she notes.
So what exactly is "never COVID"? Lawerence Young, a professor of molecular oncology at Warwick University, tells CNBC that "never COVID" refers to "individuals who have clearly been exposed to close contacts in their household who are infected, but who themselves are resistant to infection.”
According to early data, these individuals have naturally acquired immunity from previous infections with common cold coronaviruses. Around 20% of common cold infections are due to common cold coronaviruses, Young shares.
However, “why some individuals maintain levels of cross-reactive immunity remains unknown.”
Another factor that may play a role in someone not developing COVID: their COVID vaccination status.
The role of vaccines
COVID vaccines and booster shots have been proven to reduce severe infections, hospitalizations and deaths among most Americans including those that are immunocompromised. They have also proven to be largely effective against known variants of the virus. But what role do they play in people that seem to never get COVID?
Andrew Freedman, an academic in infectious diseases at Cardiff University Medical School, tells CNBC that why some people get COVID and others don’t “is a well-recognized phenomenon and presumably relates to immunity from vaccination, previous infection or both.”
“We know that many people have still caught (mostly mild) Omicron infection despite being full vaccinated, including [having had] a booster. However, vaccination does still reduce the chance of catching Omicron and responses do vary from person to person. So some people catch it and others don’t despite very significant exposure,” he adds.
One factor that may contribute to different immune responses to COVID is cross-reactive immunity from previous infections, according to Young. “Certainly cross-reactive immunity from previous infections with common cold coronavirus is likely to be a major contributor, particularly as these individuals may have additional immune benefits from also having been vaccinated.”
The genetic factor
Another question that many people are still searching for the answer to is why two people with COVID may respond differently to the infection. For example, one could have heavy symptoms and the other could be asymptomatic.
According to new research, the answer might lie in our genes.
“It’s a really important question,” Imperial College’s Altmann told CNBC on Wednesday.
Danny Altmann, professor of immunology at Imperial College London and his colleagues have conducted research into the relationship between genetics and the immune system and COVID-19 infection, and have found that variations between people’s immune systems “makes a difference, at least to whether or not you get symptomatic disease.”
The research, which is focused on different HLA (human leukocyte antigen) genes takes a deeper look at how these can affect one’s response to COVID.
“The key genes that control your immune response are called HLA genes. They matter for determining your response on [an] encounter with SARS-CoV-2. For example, people with the gene HLA-DRB1*1302 are significantly more likely to have symptomatic infection,” Altmann adds.
Further studies into never COVID individuals will provide a better understanding of the immune response to SARS-CoV-2, Young insists. It will also enlighten researchers on “what facets of the cross-reactive response are most important, and how this information can be harnessed to generate universal variant-proof vaccines.”
For more info about COVID-19 safety, visit U.S. Centers for Disease Control and Prevention.
