If you mean Pneumovax, that's given to high risk people once before the age of 65, and once after 65 (which is considered high risk), IIRC. I'm not familiar with any other pneumonia vaccine that is repeated after 3 years....
That has to be the shot I got since I am a high risk as I have hep C from a blood transfusion when I was a teen. I was told in 82 I had non A non B hep. I try to keep myself as healthy as I can as my immune system isn’t what it used to be.