not necessarily instantaneous or complete at every point where the virus enters the body. SARS-CoV-2 commonly enters through the respiratory tract, where the virus encounters tissues in the nose, throat, and airways. A person may become infected if the virus establishes itself before the immune system can prevent it from multiplying.
The outcome depends on several factors, including the amount of virus encountered, the person’s existing immunity, the characteristics of the circulating variant, and individual differences in immune function.
This explains why a vaccinated person may test positive despite having
There’s more to discover. Continue to the next page for the rest of this article.
