…your immune system is already working hard fighting any possible infection, but afterwards, your immune system is better at fighting off common ailments than before the tattoo.
Although the research’s findings do potentially support the idea that getting tattoos strengthens the immune system, it needs further testing before anyone can say for sure. As the researchers themselves note, there are other possible explanations, including the idea that people with healthy immune systems are perhaps more likely to get multiple tattoos.
Basically, don’t go getting a tattoo just because you think it’ll help protect you from the common cold. But just make sure that whatever tattoo you get, it’s one that you’d want to see for a very long time.