A milliliter of blood contains about 15 individual drops. For a person with human immunodeficiency virus (HIV), each drop of blood could contain anywhere from fewer than 20 copies of the virus to more than 500,000 copies. Called the viral load, this is what is measured to allow clinicians to understand how patients are responding to anti-viral medications and monitor potential progression. The time-consuming viral load testing needs to be repeated several times as a patient undergoes treatment. Now, a research team has developed a time and cost-efficient digital assay that can directly measure the presence of HIV in single drop of blood.