Covid, who have somehow managed to avoid testing positive. The simplest explanation is that these people have never come into contact with the virus, a report by The Conversation said.
And, this could be because such people have been shielded during the pandemic. A theory around why certain people have avoided infection is that, although they are exposed to the virus, it fails to establish an infection even after gaining entry to the airways.
This could be due to a lack of the receptors needed for SARS-CoV-2 to gain access to cells. Once a person does become infected, differences in the immune response to SARS-CoV-2 play a role in determining the severity of symptoms.
It is possible that a quick and robust immune response could prevent the virus from replicating to any great degree in the first instance, researchers said.