I am an anti vaxxer for years but my sister (amazing mom of an adult Autistic son who started a charter school for him) taught me to get the titer level in the blood measured first. She called night before my first son’s Dr appt. Do you know, it came back natural immunity from Measles! His titer was 1.8 and you needed it to be over a 1 to be naturally immune. So I waited a year. Did the titer again and it fell to 0.4. He is fine today. My 4th child had same titer.