- James Gallagher
- Health and Science Editor – BBC
I hope this blood sample contains answers, because I have a burning question: Did I never have the coronavirus?
That someone might avoid getting infected with it seemed exceptional. The virus has swept across the world since it appeared in China nearly three years ago. And the new variants kept getting better at infecting us. Even vaccines only reduce the severity of the virus and do not give us an impenetrable shield.
But I kept going to work all that time, even during the lockdowns, and the virus hit the rest of my family hard, and yet I didn’t get sick. I am by no means the only person who has not developed symptoms of Covid and has not tested positive. An estimate published last summer suggested that one in 10 people in the UK had not yet been infected.
So what is going on? Does my body, and the bodies of people who have never had COVID, contain some secret to fighting the disease?
There are three general possibilities if you think you never had the virus:
- To be wrong, you actually had the virus but didn’t realize it
- You should not have touched him
- Or your body has an additional defense mechanism that has successfully countered it
“There are a lot of people who say they never had Covid,” says Dr. Lindsey Broadbent, a virologist at the University of Surrey in England. “Most of them are probably wrong, they may have been infected but it didn’t result in any symptoms.”
“But we know that there are some people who never became infected, even among those who work in a high-risk environment, such as nurses.”
A study of people who took regular Covid tests found that half of those infected with the Omicron variant did not realize they were infected, or attributed mild symptoms to another cause.
The blood sample—which it hurt me to extract from my index finger—will determine whether or not I, too, am making a fool of myself. I put the sample in a small vial and mail it to a research lab for analysis of the mixture of antibodies it contains.
Antibodies are part of the immune system, and act like projectiles that stick to viruses, preventing them from infecting the body’s cells, and telling the rest of the immune system to kill the virus.
Different types of antibodies stick to different parts of the virus, and the test focuses on two of them:
- Antibodies that attach to a protein on the surface of the virus called a spike protein.
- Antibodies that stick to the virus’s inner layer – called the nucleocapsid – and which protect the virus’s genetic code.
All vaccines used in the UK train the body to attack only the spike protein. Even a year following my last booster dose, the test showed that I had elevated levels of anti-spinal protein antibodies.
The body learns how to attack other parts of the virus only when it encounters the virus itself. If I have nucleolar capsid antibodies in my blood, that means I have had a covid infection before.
The test result is negative, and so the idea that I never had Covid has crossed its first hurdle.
Professor Mala Maini, professor of viral immunology, invites me into her laboratory at University College London to examine the results.
“It might mean that you weren’t infected at all, but it might also mean that your body made antibodies to the nuclear capsid and then they disappeared from your blood,” she tells me.
image copyright James Gallagher
Professor Mala Maini explains the results of a blood test to James Gallagher
However, none of the COVID tests I have taken have come back positive, even though I:
- I’ve been taking rapid swab tests twice a week for much of the pandemic so I can go to work
- I took PCR tests, or rapid tests, whenever I had symptoms
- I was getting tested on a daily basis when my family members got sick with covid
Professor Maini’s conclusion was as follows: “Adding this to the result of the anti-nuclear capsid antibody test indicates that you may not have had a full-blown infection.”
‘You may have had what we call an abortive infection.’
prior immunity
The idea of an aborted infection means that you are targeted by the virus, and the virus even manages to reach the places needed to start the infection, but your body traps it before it can spread.
We know this happens from studies that have infected people. During these experiments, the virus was sprayed into the noses of healthy volunteers, yet of the 34 people who participated in the study, only half of them became infected.
The first line of protection is the innate immune system. This is our body’s automatic defense. This device cannot “remember” different virus infections, so every time an infection occurs it is like the first time for it. But it works quickly and can stop or stop the spread of infection.
Dr. Broadbent explained this by conducting experiments in which she used mini-lungs that had been grown using human cells, and tried to infect them with the virus.
“We found one person that we mightn’t infect,” Broadbent says.
The other half of the immune system is known as the adaptive, or adaptive, immune system, which learns and improves with practice. And here comes the role of vaccines that prepare the body to fight Covid.
“Maybe the vaccines have done their job perfectly and give you very good immunity,” says Professor Maini.
But vaccines provide only limited protection once morest infection with the virus, and it is quickly wearing thin. There were also no vaccinations during the first year of the epidemic.
However, there are other ways in which this part of the immune system can stop infection.
Blood samples taken from hospital workers before the pandemic showed that some of them already had what are known as T-cells. These cells act as sentinels, checking other cells for signs of infection. And if they find an infected cell, they kill it.
Even before the first cases arrived in the UK, some people had these Covid-fighting cells in their blood. This is most likely caused by the common cold coronavirus, which is very similar to the COVID-19 virus.
“If you have young children going to school, it is very likely that you have been exposed to these viruses in previous years,” Professor Maini tells me.
“If you have these T cells on alert all the time, they can act much more quickly and kill the infection before it shows up in the test result.”
The hope is to develop a new generation of vaccines that can mimic this pre-existing immunity.
“If we can get the T-cells to stick to the interior of the virus, and then elicit that response in the nose, airways and lungs, there is a much better chance that they will succeed in aborting the infection before it spreads,” says Prof Maini. “That’s the goal.”
My hunch tells me that the flood of microbes each toddler brings from nursery to their already tired parents may have helped me stave off Covid.
Are there other explanations?
There are two other possibilities, but one does not apply to me, and the other is very rare.
Some people are never exposed to the virus because they have stopped socializing. And I’ve interviewed people who self-isolate for nearly 1,000 days, usually because their immune systems are weak, which makes them more fragile. This does not apply to me, as I used to take the train to work during the epidemic, and even slept next to my little boy in bed during his illness.
The second idea is the genetic immunity that occurs with other diseases.
A well-known example is the human immunodeficiency virus (HIV). There are a small and rare number of people born with a genetic mutation that completely protects them from the virus. Called CCR5 for short, this mutation occurs in part of their genetic code and changes the “locks” in their body’s cells so that HIV cannot break through. This was taken advantage of in the treatment of some patients infected with the virus, and it was found that similar mutations were able to prevent the entry of the Corona virus into the cells of some people’s bodies.
“The number of people who have this kind of genetic resistance is very small,” says Dr. Broadbent.
Will I be safe from covid this winter then?
So can I and other people who haven’t contracted the virus feel confident as the Christmas season approaches, or are we really at greater risk?
The protection conferred by the vaccine means that the chances of infection that result in severe disease symptoms become slightly less, even if the vaccine cannot completely stop the infection.
But some research, including a study conducted in Switzerland, indicates that being infected with the virus and receiving the vaccine – or what is called hybrid immunity – results in the strongest immune response.
So Professor Maine warns me that I might be “a little more susceptible”.
Dr. Broadbent agrees, saying, “If you think you haven’t had it yet, that doesn’t mean you’re resistant to it..Most likely, you’re lucky.”
Personally, I suspect that writing this article will tempt fate, ensuring that I will catch Covid by Christmas!
