I remember a faded yellow booklet, about the size of a wallet, that my mother used to pull out once a year at the doctor’s office to record my vaccines. Today, nurses document my children’s vaccination history in electronic health records that will likely follow them to adulthood.
To eradicate a disease—such as polio or measles—healthcare workers need to know who was vaccinated and when. Yet in developing countries, vaccination records are sparse and, in some cases, non-existent. For example, during a rural vaccination campaign, a healthcare worker may mark a child’s fingernail with a Sharpie, which can wash or scrape off within days.
Now, a team of MIT bioengineers has developed a way to keep invisible vaccine records under the skin. Delivered through a microneedle patch, biocompatible quantum dots embed in the skin and fluoresce under near-infrared light—creating a glowing trace that can be detected at least five years after vaccination. The work is described today in the journal Science Translational Medicine.