Washington state has not found any definitive cases of young people who’ve experienced myocarditis or pericarditis caused by COVID-19 vaccines, according to state Department of Health officials.

The DOH said earlier this week that it was investigating a small number of cases in which patients reported post-vaccination symptoms of heart inflammation. But so far, none of these cases have been linked to the vaccine, said Dr. Scott Lindquist, the state’s epidemiologist for communicable diseases, at a weekly news briefing Wednesday.

State health officials have asked for assistance from the U.S. Centers for Disease Control and Prevention, which is conducting its own investigation into reports of heart inflammation following vaccination.

Myocarditis and pericarditis are inflammations of the heart muscle and the membrane sac around the heart, usually caused by viral infections, Lindquist said. Symptoms include chest pain, abnormal heartbeat and shortness of breath.

Health care providers in Washington, Idaho and Oregon have been notified about this issue so they can be ready to quickly identify symptoms if more cases occur, DOH said in a statement this week.

According to the CDC’s COVID-19 Vaccine Safety Technical Work Group, which has been reviewing vaccine safety data regularly since the onset of vaccinations in the United States, a very small number of teenagers and young adults may have experienced heart problems after receiving COVID-19 vaccines. Most cases were mild, the group reported, and the CDC is still following up on them. Still, the group determined that information about myocarditis should be shared with medical providers.

The work group’s statement said there had been “relatively few” instances of the condition — rates of myocarditis after vaccination were the same as expected baseline rates — and that the reported cases may not have been related to vaccines.