Why Are Some People Covid19 Resistant?

Scientists, in a number of locations, have been exploring why some people, never appear to develop Covid19 infections (https://www.theguardian.com/world/2022/mar/02/scientists-seek-to-solve-mystery-of-why-some-people-do-not-catch-covid). One explored possibility is that the nasal early immune response in some people, is powerful enough to stop the infection taking off. In these subjects, the viral levels may never rise high enough to trigger a detectable immune response. A second possibility is, that highly-resistant folk have cross-reactive memory T-cells (Thymus-derived white blood cells) from previous coronavirus infections. Exposure to Common cold or influenza infections, may protect them from the Sars-CoV-2 virus. It's, consequently, interesting to note that almost 70% of Stockholm's blood donors have antibodies against a protein from the H1N1 influenza virus. That protein corresponds to part of Covid19's spike. It's obviously very early days, but studies on people who don't get Covid19, could lead to the development of alternative treatments to help folk who are susceptible to the virus.