When my husband moved to Germany from Russia, he had no idea whether he was vaccinated as a child or not (he very likely was, but there weren't records he was aware of and his mom died early). So he went to the doctor's to ask for titers. They said they could test that but he would have to pay out of pocket, and offered to just vaccinate him again for free. He went through all the children's vaccines - including chicken pox, which wasn't around when we were kids (90s). It is the simpler, more accessible, and cheaper alternative to titers.