It does seem that close contacts of infected people acquire T-cell immunity even without infection, but at least 90 days after exposure there does not seem to be a decreasing trend: https://www.nature.com/articles/s41467-021-22036-z
It does seem that close contacts of infected people acquire T-cell immunity even without infection, but at least 90 days after exposure there does not seem to be a decreasing trend: https://www.nature.com/articles/s41467-021-22036-z