It is possible for nausea, diarrhea, and loss of appetite to be side effects of the Moderna vaccine, typically appearing around 10 days after receiving the vaccine and lasting for a few days. However, it is important to consider other factors that may be causing these symptoms, such as the use of medications like citalopram for anxiety. In some cases, side effects from medications like citalopram can persist for a few days before subsiding. It is recommended to monitor these symptoms and consult a healthcare professional if they persist or worsen.