Have I dodged Covid and what does it mean?

I anticipation this vial of humor contains answers due to the fact that I person a nagging question - person I managed to dodge Covid?

It seems singular that anyone could. The microorganism has swept the satellite since it emerged successful China astir 3 years ago. Fresh variants person go amended and amended astatine infecting us. Even vaccines marque Covid milder alternatively than being an impenetrable shield.

Yet I worked successful the bureau throughout, adjacent successful lockdowns, and the microorganism ripped done the remainder of my household and I didn't get sick. And I'm acold from the lone idiosyncratic to person gone done the pandemic without getting the walloping symptoms of Covid oregon to person ne'er tested positive. One estimation successful the summertime suggested astir one-in-10 radical successful the UK inactive hadn't been infected.

So what's going on? And does my assemblage - and those of different "never-Coviders" - incorporate immoderate concealed to tackling the disease?

There are 3 wide possibilities if you deliberation you've dodged the virus:

"There are a batch of radical saying, 'I've ne'er had 'Covid-the-disease'. Most astir apt aren't right, they whitethorn person been infected and it conscionable didn't effect successful immoderate symptoms," Dr Lindsay Broadbent, a virologist astatine the University of Surrey, tells me.

"But we bash cognize determination are conscionable immoderate radical who person ne'er been infected, adjacent successful precocious hazard environments specified arsenic nurses," she adds.

One survey of radical being regularly tested recovered fractional of those catching the Omicron variant remained blissfully unaware oregon enactment their mild symptoms down to thing else.

My humor - painfully milked retired of my scale digit - volition find whether I person been deluding myself too. I seal the humor successful a vial and station it to a probe laboratory for investigation of the substance of antibodies it contains.

Antibodies are a portion of the immune system. They enactment similar missiles that instrumentality to viruses. This stops them infecting our body's cells and tells the remainder of the immune strategy to termination the virus.

Different antibodies instrumentality to antithetic parts of the microorganism and the trial focuses connected 2 of them:

All the vaccines utilized successful the UK bid the assemblage to onslaught lone the spike protein. Even a twelvemonth aft my past booster, the trial shows I person precocious levels of anti-S antibodies.

Your assemblage learns to onslaught the different parts of the microorganism lone erstwhile facing the microorganism itself. If anti-N antibodies were successful my humor that would mean I'd been infected with Covid.

I trial antagonistic and the thought I person dodged Covid passes its archetypal hurdle.

Prof Mala Maini, a prof of viral immunology, invites maine into her laboratory astatine University College London to research the results.

"It could mean that you've ne'er had the infection, but it could besides mean you've made anti-N antibodies and they've gone from your blood," she tells me.

However, I person ne'er tested affirmative despite:

Prof Maini concludes: "Put unneurotic with your antagonistic anti-N antibody test, it suggests you whitethorn beryllium idiosyncratic who has escaped a full-blown infection.

"You whitethorn person had what we telephone an 'abortive' infection."

The thought of an abortive corruption is you are exposed to the virus, it adjacent gets into the close places to commencement an infection, but the assemblage gets connected apical of it earlier it takes off.

We cognize this happens from studies that person tried to deliberately infect radical with Covid. These quality situation trials squirted microorganism up the chemoreceptor of steadfast volunteers, but successful the archetypal 34 radical to instrumentality part, only fractional really developed an infection.

The archetypal enactment of extortion is the innate immune system. This is our body's default defence. It cannot larn oregon "remember" infections, truthful each clip is similar the archetypal time. But it is truthful accelerated it tin halt an corruption successful its tracks.

Dr Broadbent demonstrated this by conducting experiments utilizing miniature lungs grown from people's cells - called organoids - and trying to infect them with the virus.

"We recovered 1 idiosyncratic that we conscionable could not infect, we were sticking bucketloads of microorganism connected these cells and determination was nary infection," she tells me.

The different fractional of the immune strategy is known arsenic the adaptive immune system, which learns and gets amended with practice. This is however vaccines hole the assemblage for warring Covid.

"It could conscionable beryllium that the vaccines worked good for you and person fixed you precise bully protection," suggests Prof Maini.

But vaccines look to springiness lone constricted and rapidly-waning extortion against catching the virus. And determination were nary vaccines for the archetypal twelvemonth of the pandemic.

However, determination are different ways this portion of the immune strategy could halt an infection.

Blood and lung samples taken from infirmary unit before the pandemic, showed immoderate already had protective T-cells. These are similar sentinels that inspect different cells for signs of infection. If they find a contaminated cell, they termination it.

Even earlier the archetypal cases arrived successful the UK, immoderate radical had these anti-Covid soldiers successful their bodies. They are astir apt the effect of catching different communal acold coronaviruses, which are intimately related to the Covid virus.

"If you person young children astatine school, it's precise apt that you would person been exposed to these successful the preceding years," Prof Maini tells me.

"If you've got these pre-existing T-cells acceptable and waiting past they tin enactment overmuch much rapidly and bring down the corruption earlier it becomes affirmative connected your test," she adds.

The anticipation is simply a caller procreation of vaccines tin beryllium developed that mimic this pre-existing immunity.

"If you could marque T-cells against the interior regions of the microorganism and get those responses successful the nose, airways and lungs there's a overmuch amended accidental they could abort the corruption earlier it takes off, that's the goal," says Prof Maini.

My gut feeling is that the torrent of bugs each toddler brings location from nursery to plague their already weary parents helped maine dodge Covid.

There are 2 different possibilities, but they either don't use to maine oregon are incredibly rare.

Some radical person ne'er been exposed to the microorganism due to the fact that they person shunned interaction with different people. I've interviewed the super-shielders who person isolated themselves for astir 1,000 days, often due to the fact that they person weakened immune systems that permission them much vulnerable. This isn't maine aft getting the bid to enactment passim and adjacent sharing a furniture with a sickly toddler.

The different thought is familial invulnerability, which does hap with different diseases.

The celebrated illustration is quality immunodeficiency microorganism (HIV). A uncommon fewer are calved with a fortunate familial mutation that wholly shields them from the virus. A mutation successful a conception of their familial codification - called CCR5 - changes the locks connected our body's cells truthful HIV can't get inside. This has been utilized to cure immoderate radical of HIV and akin mutations person been shown to lock coronavirus retired of people's cells.

"It's incredibly, incredibly tiny numbers that person immoderate benignant of familial resistance," says Dr Broadbent.

So for immoderate of america that person inactive not caught the virus, tin we spell into the festive play with assurance oregon are we really the astir at-risk?

The extortion from the vaccine means that the chances of being severely sick are greatly lowered adjacent if it cannot halt the infection.

But research, including a survey successful Switzerland, suggests having had the microorganism and catching Covid - known arsenic hybrid immunity - gives the strongest immune response.

"So it whitethorn mean that you are a spot much astatine risk," warns Prof Maini.

Dr Broadbent agrees: "If you don't deliberation you've had it up to now, it does not mean resistance… chances are you're lucky."

Personally, I fishy penning this portion has tempted destiny truthful ensuring I drawback Covid by Christmas!

Follow James connected Twitter, Inside Health was produced by Beth Eastwood.