If you’re young, live in a capital city in Australia and have left your house since Christmas, chances are you’ve been struck with COVID-19. But we all know one, two or loads of people who’ve been out and about like the rest of us and have inexplicably managed to avoid illness.

They may have been dining out, dancing out, living in houses with Omicronny family members or housemates and somehow tested negative every damn time. Literally how though???

Are they just lucky or are they superhuman immunicorns? It’s truly baffling and turns out it’s baffled scientists too. But there are a few possible explanations.

Vaccines can work very, very well

COVID-19 vaccines are most effective at preventing serious illness or death from the virus — above 90 per cent if you’re double dosed, although efficacy wanes over time.

For some however, being up to date with vaccines could make your immune system so strong that it can neutralise the virus altogether if exposed. Two doses of Pfizer, for example, are 58 per cent effective against infection at their peak.

Previous infection

We know the immune response previous infections triggers is not as strong and doesn’t last as long as the response triggered by vaccines, but it doesn’t do nothing. If you think you haven’t had it yet, it is possible you did but were asymptomatic.

Up to one in three infections may be asymptomatic so it’s likely many of us have been infected and didn’t realise.

However, you could still get it again. Your immune system will be better at fighting the virus immediately after infection but your cells have a memory, so to speak, and after time will start to forget how COVID looks and behaves.

COVIDSafe Habits

This seems obvious but think about it: if you’ve been following health advice and socialising mostly outside, with other triple-vaxxed people, working from home, rarely commuting, not interacting with a wide variety of people and following COVIDSafe rules like wearing masks as we all should then it sort of makes sense you haven’t been sick.

You could just be a conscientious citizen and we thank you for that.

Everyone’s immune system is different

It’s true, no two are the same and they can be affected by a myriad of factors on any given day including: diet, lifestyle, whether you’re sick with something else or whether you have a condition that causes you to be immunocompromised. It’s also largely dictated by genetics — some people are just produce better antibodies against some viruses and COVID is no exception.

One UK study exposed 36 healthy young adults aged 18-29 with no prior infection or vaccination to COVID-19 via nose swab to see what would happen.

Only 18, or 53 per cent, of the subjects became infected and their viral loads rose steeply and peaked at about five days post-inoculation.

Another quarter briefly tested positive for a low viral load which suggested their immune systems quickly produced antibodies which shut the infection down tout suite.

The other quarter never tested positive, which means it’s likely a very small group of people carry a natural genetic resistance.

Scientists know this is a thing because it’s happened to other prevalent viruses. For example we know about 10 per cent of people are naturally immune to HIV due to genetic mutations in a certain gene.

If you’ve not had COVID, you might be the key to eradicating it

The UK study was published in February so scientists’ interests were piqued over the potential naturally immune people offer for new defences against the virus.

Experts said examining people with so-called “super” immunity could also help inform the development of vaccines and therapeutics.

The University College of London published a study of UK healthcare workers in late 2021 which found some exposed to the virus were able to rid their bodies of it before they even produced specific antibodies.

This was likely because they had been exposed to other human coronaviruses (remember, COVID-19 is one of many that have been around) similar to others that caused flu-like symptoms. This helped their bodies recognise the novel coronavirus as a threat and target genetic elements they’d seen before.

Researchers said the T-cells (a line of defence that works to stop the spread of infection once the virus is already in the body) produced by both vaccines and a previous COVID infection attacked the external, and unfortunately highly-mutable, spike protein of a virus. However the T-cells in these special healthcare workers in the study instead targeted the virus’ internal bits.

If these T-cells were also put into COVID-19 vaccines the vaccines could be even more effective, especially against new variants.

So maybe it’s good COVIDSafe practice, maybe it’s vaccines and maybe she’s just born with it. Either way if you haven’t had it, consider yourself blessed.