A new analysis argues that measuring vaccine effectiveness is complex. Injected vaccines may not provide immunity in the nose and lungs, which could explain why the numbers on their effectiveness can be confusing and inconsistent.

We often hear about vaccine effectiveness, but how are these numbers calculated? Experts argue that we need to look beyond simple statistics and consider basic medical facts. For example, injected vaccines mainly create immunity in our blood, not in the lining of our nose and lungs. This is a problem for viruses that enter the body through the air we breathe. Our first line of defense is in these airways, known as mucosal immunity. Since injected vaccines do not create strong protection there, it is difficult to accurately measure how well they work at preventing infection. This might be why the official estimates of their effectiveness can often seem confusing or inconsistent.

Original Author: Eyal Shahar | Source: Brownstone Institute