How does immunity work?
There has been a lot of info in the media about immunity to covid, do we have long-lasting immunity if we are infected? The short answer is yes and this is why.
Our immune system has multiple ways it fights off pathogens like viruses. We have 2 major categories of immune cells that are part of the “acquired” immune response, meaning that they only become activated when we are infected with something. These 2 categories are:
B cells – make antibodies
T cells – directly fight pathogens by killing our infected cells
We have millions of B and T cells in our lymphatic tissue like lymph nodes and the spleen and they will become activated when they recognize a specific pathogen, they will proliferate themselves and then attack the infection in various ways.
There are subdivisions of T cells that are activated, Helper T cells and cytotoxic T cells. The helper T cells “help” by activating B cells and cytotoxic T cells. The cytotoxic T cells are the ones that kill our infected cells. They kill our cells because viruses can only replicate inside of our cells, so killing infected cells stops the viruses from being able to replicate and infect other cells.
When we produce antibodies to a specific pathogen, those antibodies don’t stay in our body forever, they help to neutralize pathogens during the acute infection and then once the infection is gone, the antibodies will break down.
So if you hear in the media that antibodies to covid drop really quickly, that is true, HOWEVER, that does NOT means we no longer have immunity! This is because something else happens….
Our helper T cells, Cytotoxic T cells and B cells can form MEMORY cells. These are a subpopulation of cells that proliferated during the infection and they recognize that specific infection and those memory cells will stay in the lymph nodes and spleen for many many years! Then, if you come in contact with that virus again, the memory cells are activated and kill the infection very quickly, this is called a secondary immune response and you most likely won’t even have symptoms. Our immune cells are killing things all the time and we are, for most, part not even aware it is going on.
Another question then is, how are some people becoming re-infected with covid? Covid, like every other virus ever, mutates and changes over time as it replicates in different individuals. When it mutates then some of the antigens (surface molecules that our immune system recognizes) are different. Then we will go through the infection process again but usually it is less severe if you have memory cells to SOME of the antigens. Common cold viruses mutate all the time and this is why we almost all have at least a few colds every year.
There are multiple strains of coronaviruses that have existed for years. People that come into contact with it that are asymptomatic or have very few symptoms, most likely have been exposed to similar coronaviruses before. This is one reason why it is actually beneficial to be exposed to the endemic pathogens in our environment. If it doesn’t kill you then it actually does make your immune system stronger! If it does kill you, then, well, that sucks haha. And why we are having lockdowns to try and decrease that. But we can’t really avoid all of the trillions of microorganisms that exist and being exposed to beneficial microorganisms (probiotics) can increase your immunity. Every living thing has been co-existing with microorganisms since life began about 3.5 billion years ago. So we can’t avoid them but we can use the good ones to our benefit.
Factors that affect the severity of infection
- If an infection is new – like covid, it was a new virus and many people did/ do not have immunity to it unless they have been exposed to similar coronaviruses before. Why are kids less susceptible to covid? They are basically little germ factories ha, they don’t worry about touching dirt and putting things in their mouth so they are more likely to be exposed to tons of different viruses and have most likely come into contact with all kinds of other coronaviruses already and therefore have some cross-immunity.
- Not enough protein in your diet – making antibodies and immune cells takes a LOT of protein, if you don’t have enough then your immune response will be less effective
- Not enough sleep – people with sleep disorders have a much higher chance of more severe infections. Our body sees a lack of sleep as a major stress, stress triggers the release of cortisol, a hormone that inhibits the immune response
- Chronic stress – see above point. Many students get sick during exams simply because of the stress load that triggers excess cortisol
- Lack of micronutrients – vitamins and minerals are key components of chemical reactions, all the reactions required to make the energy needed for an immune response is massive. People that only eat fast food and processed foods that lack essential micronutrients have a much higher risk of infections. Eat lots of plants!
- Comorbidities – having other health issues such as diabetes, heart disease, COPD, obesity, liver or kidney diseases, have a significantly higher chance of being more sick from any infection
- Concentration of pathogen you are exposed to – If someone directly coughs in your face you will be exposed to a much higher viral load than if you touch an object someone else touched and then you touch your face. This is why masks are being mandated now, it is simply a way of trying to reduce the viral load people are exposed to.
- Age – as we get older all of our body cells just don’t work as well as when we are younger, including immune cells
- Poor normal flora – we are covered in microorganisms that are beneficial and they live in our digestive tract and they are essential for life. Having a healthy microflora means that you have resident organisms that help fight off pathogenic organisms. So eat bacteria, probiotics and touch soil and leaves and coat yourself in the wonderful protective organisms that exist in our environment. This is one reason why I am not a fan of hand sanitizer; it kills the organisms that help protect us.