Unfortunately healthy doesn't mean severity of symptoms, nor survival, but the vast majority of deaths are people 60 and older (said to be 95%+). Some with underlying health issues, some without. More than 40% of deaths have come from nursing homes.
COVID-19 Provisional Counts - Weekly Updates by Select Demographic and Geographic Characteristics
B cells produce antibodies that are capable of binding to the virus. The body also stores long lived "memory" B cells that produce those antibodies, that attack if the virus comes back. T cells, patrol the body seeking out and destroying infected cells, to disrupt the virus’s ability to replicate. These immune cells can also endure for years. Antibodies generally have a shelf life, that is they are not long lasting. Apparently people who have more severe symptoms have more, longer lasting antibodies. But how long antibodies last has yet to be seen. T Cells however, tend to be longer lasting
Immune T Cells May Offer Lasting Protection Against COVID-19
The COVID-19 vaccines in development mainly focus on antibodies. These proteins are made by B cells and would ideally latch onto the virus and prevent it from entering cells. T cells fight infections in two different ways. "Helper" T cells prompt B cells and other immune defenses into action, "Killer" T cells target and destroy infected cells. The severity of disease can depend on the strength of these T cell responses. Killer T Cells are the soldiers, Helper T Cells are the Generals.
Antigens are like identification tags that tell your immune system information about your cells and any intruders. Healthy cells have antigens on their surfaces. They let T Cells know that they are not intruders. If a cell is infected with a virus, there will be pieces of virus antigens on its surface. This is a signal for the Killer T Cell that lets it know this is a cell that must be destroyed
B Cell and T Cell "memory" cells develop once a virus is beaten. These memory Cells are long lived and remain dormant until they recognize the same virus again. At that time the response is faster and stronger. People who have not been exposed to Covid-19 will have no memory cells, and no protection. However, some non Covid-19 infected people show signs of Covid-19 type T Cells, showing that a response to a previous Coronavirus infection may give some people a defense even if they have not been infected by Covid-19. Sars, Mers and some cases of the common cold are caused by Coronaviruses as well. Some COVID-19 patients with mild or no symptoms have generated T cells against the virus, even in patients who have no detectable antibodies. This is a good sign.
So you can't develop T Cells in any other way but by being infected by Covid-19, or possibly a different Coronavirus. But remember, Covid-19 is called a Novel Coronavirus, that is, it had never been detected before, and is different to any previous Coronavirus. There could however be some crossover, hence the non infected people who have similar T Cells.
I know way too much at this point, but it's good to have scientific data, and not just "I heard"...
A Guy
. That's me being simple minded in my conclusion that healthy people survive this coronavirus. Oh well...we still have much to learn...Scientists don't even know how the brain works which opens the many different illnesses that people have.
