How come some infections can cause severe symptoms in one patient and be asymptomatic in another?

Question

How come some infections can cause severe symptoms in one patient and be asymptomatic in another?

In: Biology

Answer 1

Some people have underlying conditions that make them more susceptible to more severe form of infections. With covid-19 people who have existing cardiovascular disease or type 2 diabetes are more susceptible to becoming really sick as they have high levels of existing inflammation and lots levels of nitric oxide. They have also noticed that people with higher levels of melatonin seem to get less severe forms of this disease…as we age we gradually make less and less melatonin.

Some people just have more robust immune systems as well.