I’m also concerned about potential side effects from the vaccines, including impact on fertility.
But I’m guessing they were talking about the difference between effective immunity (asymptomatic infection allowing continued spread) and sterilizing immunity (completely stopping the virus from causing an infection:. https://www.verywellhealth.com/covid-19-vaccines-and-sterilizing-immunity-5092148
That’s new information to me and I appreciate the clarification of the term “sterilization”.