New Study Links Tattoos to Swelling, Reduced Vaccine Efficacy

In Brief

• A new study finds that tattoo inks can accumulate in lymph nodes and trigger prolonged inflammation.
• Researchers also found that tattoo inks can weaken immune response to certain vaccines.
• The findings suggest potential effects on humans, and calls for further human-focused research.

If you’re into tattoos, you might need to hear this. A new study has shown that tattoos can induce inflammation and reduce response to some vaccines. Although further studies are required, the current implications are far-reaching and deserve attention.

The study investigated how tattoo inks enter the lymphatic system and get accumulated in the lymph nodes, thus affecting immune cells. It also examined the long-term effect of the ink on immune responses to vaccines.

The results show that tattoo inks are quickly collected in lymph nodes, causing cell death leading to persistent inflammation that could last months. This in turn reduced immunity messenger ribonucleic acid (mRNA) vaccines for the coronavirus disease 2019 (COVID-19) at the tattoo site.

Picture of how *tattoo ink is transported by the lymphatic system and accumulates in the draining lymph node.* Source: PNAS

Tattoo Ink Can be Harmful Long-Term

Tattoos are widely used for different reasons such as aesthetics, self-expression, or commemoration. An estimated 20-30% of adults in many western countries have at least one tattoo. Younger adults have more with no idea of the potential harm tattoos can cause to them.

Tattoo inks are insoluble mixtures introduced into the skin as dyes. Colored inks are even more complex mixtures containing pigments meant for industrial applications such as plastics and paints. Despite the widespread use, not much is known about their effect in the long-term

While scientists already know that macrophages in the skin engulf tattoo pigments and store them in lymph nodes, not much is known about the effects. Using a mouse footpad tattoo model, the researchers studied the behavior of commercial black, red, and green inks after injection.

Results showing how *tattoo ink induces macrophage death*. Source: PNAS

They found that inks kill macrophages — large white blood cells that destroy harmful things in the body. This opens the door to inflammation that could persist for months, and also reduces immune response to Covid-19 vaccines.

Tattoo Ink Harm Transferable to Humans

From the findings of the study, tattoo inks can be harmful over a long time, especially if more are continuously added to the skin. While the study was only conducted using mice and human macrophages, the scientists believe the same effects could be found in humans.

Red and black inks were found to be particularly dangerous to the immune system, and are believed to increase the chances of having cancer. Further studies are required to confirm in humans, but it would be better to not find out.