(Portland, OR) -- More than 20 measles cases are confirmed in Oregon and health officials are worried there might be more. This is the worst measles outbreak since 2019. The increasing rate of children who aren't being vaccinated is allowing the disease to spread. Measles is one of the most contagious diseases. There can be serious side effects and in rare cases it can be fatal. Health officials are advising parents to get kids vaccinated. If they have concerns about the safety of the vaccines, they should talk with their health care providers.