If you’ve yet to catch COVID-19, over two years into the pandemic that has swept the world, you may well be one of the rare people who are naturally immune to the disease.
Either that or, as one Korean doctor suggests, you have no friends. The vice president of the Korean Vaccine Society later deleted his controversial Facebook post, saying his comments were meant to be taken “metaphorically”.
All jokes aside, scientists have long suspected that there are certain individuals who have immune systems that are particularly adept at fighting the SARS-COV-2 virus.
The BBC reported, in July of 2020, that there is a percentage of the population who appear to have T cells — the immune cells tasked with identifying and killing invading pathogens and infected cells — that specifically seek out COVID-19’s spike protein layer.
The weirdest thing about this is that these T cells — of which our bodies produce trillions of possible versions to fight different infections — were present in these people long before COVID-19 ever infected humans.
Scientists suspect that people with these cells are actually fairly common — with 40-60% of the population thought to have them.
Later studies appear to support this theory, with one conducted on London healthcare workers during the first wave of the pandemic, found that around 15% of people who had been exposed to the virus did not record an infection. When they looked more closely, they found that these people had an increase in the T cells responsible for fighting COVID, suggesting that they already had these cells to begin with which targeted the virus before it could take hold.
There is also evidence to suggest that your genetic makeup could also play a big role in whether or not you catch COVID. Work at Imperial College London has found that people without certain human leukocyte antigen genes are far more likely to have asymptomatic or no infection from COVID.
So, is it just a genetic or immune system lottery as to why you’ve not managed to catch COVID? Not quite.
Vaccines and Testing Issues With COVID
It goes without saying that vaccination plays a huge role in your body’s response to COVID, but there are many factors at work that also impact infection.
Vaccination rate and timing can be a big one. Those who have received at least two doses of a COVID vaccine are up to five times less likely to catch COVID than those who are unvaccinated.
This protection is a little shakier when compared to newer variants, like Omicron and its variant, BA.2, however a booster jab has been shown to push that protection back up. A third dose has been shown to make up 50% less likely to catch COVID than without it.
Timing of the doses is also important. Immune protection rises dramatically two weeks after vaccination, however, we do see a decline in protection after three to six months. That immunity however remains higher with people who have had three doses than people who have just had two.
If you were, for example, to be exposed to COVID in the month following your second or third dose of the vaccine, the chances of catching it are much, much lower. This could explain why some people have not contracted the virus following exposure.
There is also the fact that a COVID infection may simply have been missed. Rapid Antigen Tests, most of which only identify viral load in the nose, are less accurate than PCR tests, which also test for viral load in the throat.
COVID-19 appears to show up first in the throat, however, it also disappears from there first. Testing with a RAT during the period where the virus has yet to significantly infect the nasal passage could mean missing the infection and presuming you have a cold or something similar instead. That’s if you’re presenting symptoms at all, and not everyone does.
Couple this with the fact that testing almost collapsed in parts of Australia after the Christmas period, with RATs skyrocketing in price and PCR testing queues stretching on for hours. It’s no wonder that Immunologist Stuart Tangye believes we simply don’t know how many COVID infections have happened in Australia and who exactly has had the disease.
“I’m sure we missed a lot of positive cases over December and January too, where there was a supply and demand problem in terms of getting tests,” he told the ABC.
This all being said, there are simply those who, for one reason or another, are immune to the virus. This has been noted in other diseases, like HIV, where a tiny percentage of the population have genetic mutations in their immune system that protect against this virus, and could be the same with COVID.
Scientists are still trying to work out exactly how these people resist the virus, and some are actively seeking out those people for studies that they hope could give some insight into new vaccines and new treatments that may be far more long-lasting and effective in the fight against COVID than those we already have.
For now though, while your overly-confident mate is probably wrong in their claims of being “immune” to the virus, there may actually be some truth to it if they just happen to be one of these lucky people. If so, maybe get them on down to the nearest immunology research lab.