Symptom severity can be influenced by many different factors. For other viruses, oftentimes more exposure leads to more rapid disease and a higher likelihood of severe symptoms. Also, people who are older, have a worse health status (e.g. cancer patients, people taking immunosuppressive drugs, people with chronic health problems, or are otherwise immune compromised) are usually more likely to get sicker.
In the case of COVID-19 specifically, it is hard to know who has had more virus from any single interaction. However, we have seen that healthcare workers who are frequently taking care of sick patients are at higher risk of catching it themselves. It is recommended to stay at least 6 feet away from everyone and also reduce the time you are exposed to everyone as much as possible, since even people who do not exhibit COVID-19 symptoms when infected can spread the virus.
Drafted 3 April 2020