Studies link myocarditis cases to mRNA vaccines

Matt Woodley

30/06/2021 4:38:27 PM

But while the two new papers showed an association, neither was able to determine whether the vaccines caused the heart condition.

Moderna and Pfizer vials.
An association with rare cases of myocarditis was found between both Moderna and Pfizer COVID vaccines. (Images: AAP)

Two new studies out of the US have tracked cases of myocarditis that developed within days of people having either the Pfizer or Moderna mRNA COVID-19 vaccines.
One study describes a group of seven patients with acute myocarditis over three months, four of whom had recently received an mRNA vaccine.
All of the four cases (three men aged 23–36 and one 70-year-old woman) developed the condition 1–5 days after receiving their second dose of an mRNA-based COVID-19 vaccine and were hospitalised with severe chest pain.
The cases had biomarker evidence of myocardial injury and cardiac MRI findings typical of myocarditis, but were discharged within 2–4 days of hospitalisation following conservative treatment with nonsteroidal anti-inflammatory drug and colchicine (one patient received corticosteroids).
In the second study, 23 males aged 20–51 presented four days after vaccination (seven Pfizer, 16 Moderna), 20 of which occurred following the second dose. Among the three patients presenting after an initial vaccine dose, all had confirmed COVID-19 infection more than two months prior to vaccination.
The cases occurred between 1 January and 30 April against the backdrop of 2.8 million doses of mRNA COVID-19 vaccines administered to US military personnel. Cardiac symptoms resolved within one week of onset for 16 patients, but seven continued to have chest discomfort at the time of publication and follow-up is ongoing.
Professor Chris Semsarian, a cardiologist at the University of Sydney, Royal Prince Alfred Hospital, said while both studies show an association of vaccination with myocarditis, neither implies causation.

‘The incidence of myocarditis in these studies is exceedingly rare amongst those who are vaccinated, and is infinitely outweighed by the striking benefits of COVID-19 vaccination in preventing cardiorespiratory failure and death, especially in those with pre-existing cardiovascular disease,’ he said.

‘The complication of myocarditis is exceedingly rare in these two studies – 27 cases among over three million vaccinated.

‘The studies should remind clinicians that all vaccines have rare complications, and in this case, cardiac symptoms such as chest pain or shortness of breath should be investigated if they occur post-vaccination.

‘Despite exceedingly rare potential complications, population-wide vaccination remains the key to overcome the COVID-19 pandemic.’
Likewise, Medical Lead of the Melbourne Vaccine Education Centre Dr Daryl Cheng said that although reported myocarditis or pericarditis cases after mRNA COVID-19 vaccinations are above expected background rates, they are a ‘rare occurrence’.
‘Thankfully, the overwhelming majority of overseas reported cases thus far have been mild and have made a rapid recovery,’ he said. 

‘Detecting safety signals such as myocarditis or pericarditis demonstrate that both Australian and international vaccine safety surveillance systems are robust and constantly adapting to the latest available data.
‘The main safety challenge with a large population-wide rollout is detecting and responding to signals such as these which were not evident in a clinical trial.

‘Australians want to know that our rollout is underpinned by a robust safety vaccine system, and any previous and future changes to the rollout system should be viewed in this context.’
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Dr Marilyn Ann Efimoff   10/08/2021 7:33:43 AM

I am concerned that these cases of Myocarditis mainly followed the second dose of mRNA vaccine. It has been suggested that a third booster will be needed. What will happen after the third dose? We need to keep a close watch on this.