A recent study published in the American Journal of Human Biology suggests that people with previous tattoo experience may have a better immune response to new tattoos than those being inked for the first time. That’s the finding if you read the open access journal article, anyway. If you stick to the headlines of recent writeups of the study, your takeaway was probably that tattoos are an effective way of preventing the common cold. (sorry to break it to you, but they’re probably not).
Something similar happened with dietary salt, many years ago. Now we have a nation that erroneously believes salt is bad for you.