Have COVID-19 variants finally outsmarted the vaccine? The answer is complicated. While the shots offer great protection from illness and death from COVID-19, this protection will fade over time. Getting a third dose reactivates the body’s immune system and gives you a “boost” of resistance to the disease.

“The booster dose of the COVID-19 vaccine is required to increase the level of antibodies in the body,” says Dr. Subhash Verma, Director of the Cell and Molecular Biology graduate program at the University of Nevada School of Medicine. “[This is because] in the case of COVID-19, the level of antibodies goes down over time.”

The muscle cells at the site of the injection produce proteins, which are then taken in by immune cells. These immune cells transfer that “information” to T-helper cells, which then pass it along to Killer cells. These cells — true to their name — move on to kill foreign material in the body that matches the “description” they were given. All of this is to say that getting a third dose of the vaccine is important to help your body continue to fight off infection!