Reports of Myocarditis following COVID vaccine: Is there a concern for Indian physicians?

Two new case series published on Tuesday in JAMA Cardiology support a temporal link between second doses of the mRNA-based COVID-19 vaccines and the development of acute myocarditis within 4 to 5 days.(1,2) These findings come at a time when first mRNA vaccine (Moderna) for use in general population has been approved just few days back in India.

With vaccination drive in full swing, these case series highlighting the sequel of myocarditis after vaccination have raised several questions for the public and general practitioners alike.

Is there a proven causal link of vaccines with myocarditis? Who are more prone to developing this complication? Is the incidence of this side-effect too low to be accounted for? Does it call for delaying the second dose? The following review attempts to answer these queries.

Most of the reports about myocarditis show that affected patients tend to be young and male; present with chest pain, abnormal ECG findings, and elevated troponins; and have findings on cardiovascular magnetic resonance (CMR) imaging consistent with acute myocarditis; and to have a relatively mild clinical course.

In the study by Kim et al (1) , 7 patients suffered acute myocarditis, 4 occurred within 5 days of COVID-19 vaccination between February 1 and April 30, 2021. All 4 patients had received the second dose of a messenger RNA (mRNA) vaccine, presented with severe chest pain, had biomarker evidence of myocardial injury, were hospitalized, and had cardiac magnetic resonance imaging findings typical of myocarditis.

Another larger case report comes from the US Military Health System and describes 23 individuals with acute myocarditis who presented within 4 days after mRNA-based COVID-19 vaccination.(2) All patients were male, 22 of 23 were on active duty, and the median (range) age was 25 (20-51) years; 20 cases occurred after receipt of a second dose of an mRNA-based COVID-19 vaccine. 8 of 23 patients in this series received cardiac magnetic resonance imaging, and all 8 demonstrated findings again consistent with acute myocarditis

A causal relationship has not yet been established between the mRNA vaccines and myocarditis, though advisors to the US Centers for Disease Control and Prevention (CDC) concluded last week that there is a "likely association." The possibility of a causal link is strengthened by the timing of the myocarditis, which occurred no later than 5 days after vaccination in both studies.

"It's important for physicians to realize that this is a possible side effect of COVID-19 vaccination so they can treat it appropriately", noted Kim, the author of one of the studies. It is important to emphasize here that although this side-effect is very rare but in a densely populated country like India, it may account for a significant total number of cases and thus both the general public and treating physicians need to be educated about it before rolling out mRNA vaccines to avoid any undue alarm in this age of fake social media campaigns.

The risk of myocarditis should not be a major discouraging factor when it comes to COVID-19 vaccination, Kim stressed. "We are currently living in a pandemic, and the most effective way of limiting infection and transmission of the virus is the COVID-19 vaccinations. The vaccines have proven themselves to be quite safe. That's not to say that complications from vaccinations are not possible; however, in the case of myocarditis, the symptoms and consequences are generally self-limited within a short window."

Conservative treatment included colchicine in three patients in Kims's study, nonsteroidal anti-inflammatory drugs in two, and corticosteroids in one. All were discharged after 2 to 4 days in the hospital.

In the study on US military personnel, twenty of the men developed myocarditis after receiving their second vaccine dose. All three of those who had the complication after their first dose had recovered from a confirmed SARS-CoV-2 infection more than 2 months earlier. Of those tested for COVID-19, all were negative.

"This is especially important in the younger population—specifically, those younger than 18—and it raises questions about whether recommendations regarding vaccination should be reconsidered", noted João Cavalcante, MD, whose group published an "imaging vignette" detailing four myocarditis cases related to mRNA vaccination in JACC: Cardiovascular Imaging earlier this month.

But it could be that not all young people need a second dose because they have such a strong immune response to the first one, he suggested.

Don't 'Interrupt the March Toward Maximal Vaccination': 

In an accompanying editorial, David Shay, MD (CDC, Atlanta, GA), and colleagues note that details from published case reports, including a recent one in Pediatrics, suggest an immune-mediated mechanism to explain the relationship between mRNA vaccination and myocarditis

"At present, the benefits of immunization in preventing severe morbidity favors continued COVID-19 vaccination, particularly considering the increasing COVID-19 hospitalization rates among adolescents reported during spring 2021," the editorialists write.

Clinicians discussing immunization with patients should recognize that these case series suggest that the symptomatic events consistent with myocarditis are still very rare and appear to be self-limiting. Given the risks of COVID-19, including the risk of myocarditis from COVID-19 infection, the editors do not believe these case reports are sufficient to interrupt the march toward maximal vaccination against SARS-CoV-2 as expeditiously as possible.

Thus, at this point, the available evidence provides following take-away points for clinicians:

1. Myocarditis is a very rare sequel to mRNA vaccines.

2. There is a proven temporal association but a causal association is not yet established.

3. Most cases occur in young adults and are usually self-limiting.

4. There is no need to raise an undue alarm but at the same point one has to be vigilant about possible myocarditis symptoms in vaccinated adults in the first week-especially those receiving second dose or those receiving vaccine after recent recovery form COVID-19 infection.

5. The vaccination drive should continue uninterrupted with watchful awareness on part of clinicians and patients for alarming symptoms of myocarditis especially once mRNA vaccine starts rolling out for general public.

Refrences: from JAMA cardiology

1. Kim HW, Jenista ER, Wendell DC, et al. Patients with acute myocarditis following mRNA COVID-19 vaccination. JAMA Cardiol. 2021

2. Montgomery J, Ryan M, Engler R, et al. Myocarditis following immunization with mRNA COVID-19 vaccines in members of the US military.JAMA Cardiol. 2021