The structure of the virus itself is pretty interesting. It is round in shape with spikes sticking out, like a crown(hence the name "corona"). The virus' spikes allow it to latch onto human cells, where it begins to quickly and uncontrollably multiply itself. When it reaches an extremely large number, the amount of viruses in the cell may disrupt the cells' normal function, make toxins to paralyze our cells, or kill the cell itself, if powerful enough. In the case of COVID-19, its spikes latch on to the ACE2 receptor(a membrane protein that is capable of constricting a blood vessel and regulating blood pressure levels) and begin to multiply and disrupt the cells' normal function. The worst part is that it usually is able to latch onto the ACE2 receptor undetected, meaning that the antibodies(things that fight foreign diseases) in our bodies are unable to recognize that we are in danger until it's too late. The reason why older people who have underlying health conditions are at more of a risk of contracting the virus is because most of them have diabetes and high blood pressure problems and are required to take pills known as ACE2 Inhibitors, which is supposed to help the enzyme regulate blood pressure levels better by stimulating it more. However, since the drugs cause the protein to be more active, COVID-19 can locate and infect the cell more easily.