The question “Why is it not possible to make a cure for viruses?” comes from Heather Jones’ class. Viruses are extremely tiny particles that infect and take over our cells to create copies of themselves. We get sick because the virus damages our cells. Common viral infections include the flu, the common cold, chickenpox and cold sores. Luckily, our immune system typically finds and destroys the replicating virus — that is its job. However, this process can take several days. When you have the flu, that is a long time to feel sick! The reason it takes so long is because viruses are constantly changing. Every time you get the flu, for example, it is a slightly different virus than the one that gave you the flu before. Since every viral infection is different, the body must create tiny virus-killing fighters known as antibodies each time it encounters a new virus. This is where vaccines come in. A vaccine contains a non-infectious virus for our immune system to fight off. That way, our immune system can automatically kill off the infectious virus you were vaccinated for and you won’t become sick. Since viruses are ever-changing, scientists must constantly update vaccines with non-infectious versions of the virus’ current form. This is why we have to get annual flu shots. To make things more complicated, some viruses can avoid being killed by our immune system. When that happens, scientists develop antivirals that suppress a virus’ ability to replicate. If you get a really bad version of the flu, doctors might give you an antiviral so that your immune system has a better chance of killing the virus. Fun fact: Scientists are now working to develop viruses that can send medicine to cancer cells, or infect and kill bacterial infections, without harming healthy cells. Zachary (Zeke) Elkins is a Ph.D. student in the Division of Biological Sciences at the University of Missouri.