With the onset of the third wave of COVID 19 in India and around the world, the pertinent question that strikes me is, “Why do some people not get Covid-19 yet others keep getting infected, one wave after the other?”
Some got infected in the first wave with the alpha variant and now with Omicron, while there are still others who haven’t even fully recovered from the trauma of the delta variant and have caught Omicron.
The reason I have this question come to mind repeatedly is because too many people have asked me this, “why is it that some people keeping infected despite the vaccine and why do some not get infected at all, vaccine or no vaccine? “.
Now I will be a little direct here and say that those some people who keep getting infected are people like myself. I was first infected in August 2020 and now in the January of 2022. I am fully vaccinated but I am also at a very high risk of exposure considering the nature of my profession. So maybe citing myself as an example would not be the best thing to do but I know and have treated many who have gotten infected repeatedly over the course of the last 2 years.
It makes me curious to know why is it that the virus infects different people differently and some people not at all.
According to Utah HERO phase one study by University of Utah, once a person is infected with coronavirus, there is a 12.4% likelihood that they will infect someone they are living with. In another study from China the household transmission rate is close to 16.4% and goes up to 27.8% in spouses of the primary case.
Which means there is a significantly high chance of contracting COVID from a family member, especially a spouse. Despite all this data, there are people within families who report to never have gotten infected despite all their family members catching the virus. There are people who don’t get infected despite their spouse having been severely ill with the disease. Is it possible that they are resistant to coronavirus infection?
It is a matter of interest for a number of scientists and experts to understand why this phenomenon occurs. In fact, researchers around the world are looking to study 'Discordant couples' where one is infected and the other not affected by the virus.
More prodding into the topic, led me to find out that there are scientists who are trying to study individuals who despite having been in circumstances where they are significantly exposed to the virus haven’t contracted the illness.
These people are different from people who develop a mild infection or are asymptomatic. These are the people where the virus never enters the cell. They have some sort of a genetic makeup that prevents the virus from entering their body and causing the disease.
According to a study by the university college of London, it is the body’s T Cell immunity which prevents this. Health care workers who were highly exposed to the virus were followed to see the kind of infection and immunity they had from the virus during the first wave of the pandemic. It was found out that a small percentage never went on to test positive for COVID 19. The immunity from the virus is being attributed to T cells and another blood marker.
Our body has a range of defenses against the foreign objects. T cells form a part of our immune system and prevent the foreign substances from entering our body. It provides a long-lasting immunity in contrast to the B cell immunity (with antibody) which tends to fade with time.
It was found that in the people who don’t test positive for COVID 19, the T cells clean the virus before it can get inside the host cells (also called an abortive infection) and so the PCR test (for current infections) and antibody test (to see previous infections) are negative. It is being seen that the people who did not test positive had memory T cells from a previous infection or seasonal coronavirus infection, which protected them from COVID 19.
The results from this study are highly anticipated as it could help decide if future vaccines would be able to copy this response and prevent infection rather than just preventing severe illness and provide long-lasting immunity from the virus.
The hope is that it is deciphered before a new and more dangerous variant of COVID 19 comes up and we start all over from scratch again.
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