I guess they were successful in vaccinating a few hundred million first and a few billion after. Successful for now. 😉

Thanks for the explanation. Can you tell me why t-cell immunity would be involved in mucosal immunity? I was under the impression that mucosal immunity is completely independent and unaware of adaptive immunity and functions autonomously to neutralize common molecules it's learned about before they can make biological (toxicological) impact. I was lead to believe that mucosal immunity acts in the order of milliseconds to seconds [as in the ability the nasal passage to up or down regulate it's sensitivity to specific molecules] while t-cells are slow and take a while to recognize an infected cell, sometimes days. Is my understanding fundamentally deficient or wrong?

Once I understand how this works, I could evaluate if the impact would be negative or positive or unknown.