The headquarters of the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia.

Tami Chapel | Reuters

A key advisory body to the Centers for Disease Control and Prevention is holding a meeting Wednesday to discuss rare but unexpectedly high reports of heart inflammation in 16- to 24-year-olds after receiving their second dose of Pfizer or Moderna Covid . 19 vaccines.

The CDC’s Advisory Committee on Immunization Practices meets about two weeks after the agency announced it had seen higher than expected cases of myocarditis or pericarditis in 16- to 24-year-olds after their second Covid vaccination . Myocarditis is the inflammation of the heart muscle while pericarditis is the inflammation of the membrane that surrounds the heart.

The meeting was originally scheduled for June 18, but has been postponed to reflect the National Independence Day holiday in June.

According to the US agency, nearly 800 cases of heart problems have been reported to the vaccine safety monitoring system.

The CDC said two-thirds of the cases were in young men with a mean age of 30 years. Symptoms, which include chest pain and shortness of breath, usually develop within a few days of receiving the injection, the CDC said. Some of the reported cases may not be verified or even related to the shots, although the number of cases is still worrying, said Dr. Tom Shimabukuro of the CDC’s Immunization Safety Office earlier this month.

“We clearly have an imbalance here,” Shimabukuro said at a meeting of the FDA’s Advisory Committee on Vaccines and Related Biological Products on June 10. The FDA advisory group met to discuss safety issues related to the use of Covid vaccines in children 6 months and older.

Here’s what you need to know.

When does the meeting start?

The public session is scheduled to run from 11 a.m. ET to 4 p.m. ET, according to a draft agenda.

During the meeting, U.S. officials will provide an update on messenger RNA vaccine safety data, including possible additional cases of heart inflammation. They are also expected to discuss whether the benefits outweigh the risks for use in adolescents and young adults and potential recommendations for additional doses of Covid vaccines.

A vote on a recommendation was not included in the draft agenda.

Do the vaccines cause the disease?

Federal officials still don’t know if the vaccines are causing the disease.

The CDC’s vaccine safety group is investigating reported cardiac inflammatory conditions. It is coordinating its investigation with the Food and Drug Administration, which last month approved the Pfizer BioNTech vaccine for adolescents ages 12-15.

Moderna, whose vaccine is currently approved for people aged 18 and over, said on June 11 that it had found no link between its Covid-19 vaccine and the cases of rare heart inflammation reported in young adults. The company said it was actively working with public health and regulators to further assess this issue.

In a statement, Pfizer said it is aware of the reported cases and supports the CDC’s call for “careful assessment of suspected myocarditis and pericarditis”.

“All adverse events are regularly and thoroughly reviewed by both Pfizer and the CDC. It is important to understand that a careful evaluation of the reports is ongoing and it has not concluded that the mRNA COVID-19 vaccines are causing myocarditis or pericarditis. “It said.

What are the symptoms?

The CDC said people should watch out for chest pain, shortness of breath, or palpitations.

Men make up the majority of reported cases and most cases appear to be mild, CDC officials say. Of the 270 people who developed the disease and were discharged, 81% of them made a full recovery, according to a CDC presentation at a meeting earlier this month. By May 31, 15 people had been hospitalized, three of them in intensive care, the agency said.

It is possible that no more cases have been recorded, said former FDA chief Dr. Scott Gottlieb told CNBC on June 11, but “we probably cover the most severe cases”. He added, “If you look at the number of people who have severe cases of pericarditis, these are very small numbers right now.”

Should young people still get vaccinated?

The CDC and most health professionals say yes.

Although no link has been found between the vaccines and the disease, health experts say side effects occur rarely once a vaccine or drug is administered to the general population. The US has distributed millions of Covid vaccines which have helped contain new cases and hospital stays across the country.

“Given the risk of COVID-19 disease and the associated potentially serious complications such as long-term health problems, hospitalization and even death, the CDC continues to recommend COVID-19 vaccination for anyone aged 12 and over,” the agency said on its website .