Tattoos Alter Vaccine Responses

A PNAS mouse study shows tattoo pigments drain into nearby lymph nodes within minutes, persist for months, trigger immune‑cell death and chronic inflammation, and change antibody responses—weakening mRNA COVID vaccine responses when injected into tattooed skin while boosting response to an inactivated flu vaccine. The results are preclinical but suggest ink particles are immunologically active and not inert. — If findings translate to humans, this affects vaccine administration guidance, tattoo‑ink safety regulation, and informed‑consent messaging for both vaccination and tattoo procedures.