Research on long-term effects underway

In October 2021, Da’Vion Miller was found unconscious in the bathroom of his Detroit home a week after receiving his first dose of the Covid vaccine from Pfizer.

He knew something was wrong: at the age of 22, he had started experiencing chest pain two days after being vaccinated, followed by fatigue, shortness of breath and dizziness.

Miller was rushed to Henry Ford West Bloomfield Hospital, where he was diagnosed with myocarditis, inflammation of the heart muscle, and pericarditis, inflammation of the outer lining of the heart. Her doctor advised her not to receive a second dose of the Pfizer or Moderna vaccines.

“I was like, this is crazy,” Miller said, noting that he knows heart inflammation after vaccination is extremely rare.

Da'Vion Miller
Da’Vion Miller.Courtesy of Da’Vion Miller

Miller is among a very small group of people in the United States who have suffered from myocarditis following vaccination with Pfizer-BioNTech or Moderna Covid vaccines based on mRNA technology.

Myocarditis is a condition that has long been linked to a number of viral infections, including influenza, coxsackieviruses, as well as Covid. It has also been observed as an infrequent but concerning side effect of Covid mRNA vaccines.

Are there long-term risks of myocarditis?

Of the hundreds of millions of doses of Covid vaccine administered in the United States since late 2020, there have been approximately 1,000 reports of vaccine-related myocarditis or pericarditis in children under 18, mostly young men, according to the Centers for Disease Control and Prevention. Most of those who developed the disease made a full recovery, although research has so far only looked at their condition after several months. Some doctors wonder if it can cause permanent damage to the heart.

Today, the first research in the United States is underway, tracking the adverse health effects – if any – that may appear in the years following a diagnosis of vaccine-associated heart problems. Moderna has already launched two trials, the most recent in September. Pfizer has confirmed that at least one of its trials, which will include up to 500 adolescents and young adults under the age of 21, is expected to begin within the next two months.

The Food and Drug Administration has required drugmakers to conduct several studies assessing the potential long-term impacts of myocarditis, as part of its approval of Covid mRNA vaccines in the United States. The first research results could be published as early as next year, sources told NBC News.

Some of the trials will follow those who have developed the disease for five years, according to FDA approval letters. The trials will monitor myocarditis and subclinical myocarditis, which do not cause symptoms.

The FDA declined to comment on the Pfizer and Moderna studies because they are ongoing, but an agency official said the risk of myocarditis occurring after vaccination is “very low.”

The condition does not lead to cardiac deaths, the official said, as claimed by Florida’s surgeon general last month, which cited an unpublished analysis of state data.

“There is no evidence of an increased risk of death from mRNA vaccines compared to people who have not been vaccinated,” the official said. “In fact, evidence from well-conducted, peer-reviewed published studies suggests that the risk of death is higher in the unvaccinated for almost all age groups.”

What do we know about myocarditis and vaccines?

The vast majority of cases occur in young men, ages 16 to 24, according to the CDC. The agency did not have data on the total number of cases in young adults 24 and younger, but it estimates there were 52.4 cases and 56.3 cases per million doses of Pfizer vaccines and Moderna, respectively.

Symptoms of myocarditis include:

  • Chest pain
  • Shortness of breath
  • Feeling of having a fast, fluttering, or pounding heart

A study by Canadian researchers published Monday in the Journal of the American College of Cardiology found that men under 40 who received the Moderna vaccine had the highest risk of heart problems, usually within 21 days of the second dose. The study was observational, meaning it doesn’t prove cause and effect, but it’s one of the few studies to compare the risk of myocarditis between the Pfizer and Moderna vaccines.

Last month, Kaiser Permanente scientists found that the incidences of myocarditis after a booster dose of the Pfizer or Moderna vaccine were higher than after the first dose, but still lower than after the second.

More news on Covid and heart risks

  • A CDC report in April found that heart problems were more common after Covid infection, compared to heart problems after vaccination.
  • After a Covid infection, heart risks remain elevated for up to a year.
  • Video: CDC says waiting longer between doses of Covid vaccine could reduce risk of myocarditis.

There was no similar reporting pattern observed after receiving the Johnson & Johnson vaccine. Novavax said no issues with heart inflammation were raised during clinical trials of its vaccine.

Vaccine-associated myocarditis is usually milder than the viral type, and most people with the disease make a full recovery, said Kaiser Permanente vaccine expert Dr. Nicola Klein.

In some cases, people who have developed myocarditis after a viral infection may experience scarring along the heart tissue, reducing its ability to pump blood and move oxygen around the body, Dr. Leslie Cooper said. chairman of the cardiology department at the hospital. Mayo Clinic in Rochester, Minnesota. Cooper has joined an expert advisory group formed by Moderna to monitor the safety of its Covid vaccine.

It’s unclear how many people with vaccine-associated myocarditis will experience this scarring, he said, noting that about 20% of people with virus-related myocarditis go on to experience heart failure.

“It could be 2%. It could be 0%. It could be 20%,” he said, referring to the percentage of people with vaccine-associated myocarditis who could experience long-term cardiac consequences. “We don’t know the answer.”

The CDC recently published a study in The Lancet that looked at the health outcomes of more than 500 adolescents and young adults at least 90 days after the onset of myocarditis following mRNA vaccination.

Most improved at least three months after symptoms. Other findings from the CDC report included:

  • About a quarter of patients in the study were prescribed daily myocarditis-related medications when they were last seen by a healthcare provider.
  • Just over 100 of the patients had not been allowed to engage in physical activity.
  • In addition, 81 patients had an abnormality on their heart MRI – although this does not necessarily mean they are at risk for adverse health problems.

The CDC will follow patients who had not fully recovered for 12 months, said Ian Kracalik, lead study author and CDC epidemiologist.

Are some patients at higher risk for heart problems, such as arrhythmias? Dr. Dongngan Truong, a pediatrician at the University of Utah Health, said Pfizer researchers will try to determine the factors.

Pfizer, in collaboration with the Pediatric Heart Network, will monitor the participants for five years, according to Truong, co-lead of the Pfizer study. The Pfizer study will include people who have previously been hospitalized for vaccine-associated myocarditis, and it will also follow those who have been diagnosed more recently.

The team will also compare the patients to a subset of patients with multisystem inflammatory syndrome in children, also known as MIS-C, which is associated with Covid infection.

Truong said monitoring what happens to young people and children after Covid infections is “particularly important” to better understand the risks of the disease, compared to possible side effects of vaccines.

The Pfizer study, which will take place in the United States and Canada, has not yet started recruiting, although the research team has already identified more than 250 patients with myocarditis, she said.

The first results could be published next year, Truong said.

Scientists still don’t yet have a clear explanation of why vaccines cause the disease, according to Dr. Paul Burton, Moderna’s chief medical officer. He expects that the virus’ spike protein, once produced in the cell after vaccination, could generate a reaction in the body that can cause inflammation in the heart.

“We don’t understand yet and there’s no good mechanism to explain it,” he said.

The two myocarditis studies Moderna has launched, one of which is in collaboration with the American College of Cardiology, use public and private data from tens of millions of people who received the company’s vaccine and how they survived. came out of it, Burton said.

“Did they catch myocarditis? When did it happen ? How was he treated? How bad was it? ” he said.

Moderna is also conducting two additional studies with the European Medicines Agency which will cover five different countries. The drugmaker will evaluate the results for a year or more, Burton said, with the data to be made public around next summer.

He said he didn’t expect any “big surprises”.

In recent weeks, several new versions of the omicron variant, including BQ.1 and BQ.1.1, have begun to circulate widely in the United States, increasing the risk of reinfection, especially for those who have not yet received a dose. reminder.

“The new variants emerging that we’re seeing in the landscape are very, very contagious and pose really high risk,” Burton said. “The benefit of getting vaccinated outweighs the risks of getting vaccinated. And that’s absolutely true for myocarditis.

Klein of Kaiser Permanente agreed, saying the overall risk of vaccine-associated myocarditis is “very low.”

A year later, Miller is still experiencing symptoms, including chest pain. While it’s comforting to know his situation is rare, he said he has been hospitalized and discharged since his diagnosis, which he says has been difficult for him.

“It was a scary experience,” he said.

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