Which method is NOT used for preventing disease spread during an outbreak?

Observational studies are primarily used for gathering data and analyzing patterns related to health phenomena, such as identifying risk factors, understanding disease transmission, or evaluating the effectiveness of interventions. They do not actively prevent the spread of disease during an outbreak.

In contrast, vaccinations are designed to provide immunity against specific diseases, effectively reducing transmission. Quarantines are measures taken to isolate individuals who may have been exposed to an infectious disease, thereby limiting its spread. Public information campaigns aim to educate the public about the disease, promote preventative behaviors, and inform individuals how to reduce their risk of infection. All these methods work directly to prevent disease transmission, while observational studies serve a different purpose related to research rather than intervention.