https://www.mercurynews.com/2021/08/27/new-ucsf-study-vaccine-resistant-viruses-are-driving-breakthrough-covid-infections/

Waning immunity and ferocious contagion are known to be fueling the troubling surge in “breakthrough” COVID-19 cases among vaccinated people.

But a new UC San Francisco analysis of 1,373 Bay Area cases reveals a third, and more ominous, problem: The coronavirus is learning to outsmart our immune system.