Information for healthcare professionals on myocarditis & pericarditis following COVID19 vaccination

Myocarditis and pericarditis are both inflammatory conditions of the heart. The incidence of myocarditis is difficult to ascertain as most cases are mild and are often not well investigated.

Published 23 August 2021



Contents

  • What is generally known about myocarditis and pericarditis

  • Symptoms of myocarditis or pericarditis

  • Reporting myocarditis and pericarditis following COVID-19 vaccination

  • Treatment

  • References

What is generally known about myocarditis and pericarditis

Myocarditis and pericarditis are both inflammatory conditions of the heart. The incidence of myocarditis is difficult to ascertain as most cases are mild and are often not well investigated.


In one study from the UK it was estimated that between 1998 and 2017 there were 36.5 per 100,000 NHS admissions with myocarditis, with the numbers increasing with each year since 2004. In 2017 it was estimated that there were about 2,000 hospital admissions for myocarditis. Overall, two-thirds of cases were in men, and men were significantly younger (median age 33) compared to women. The most common type of myocarditis is an acute lymphocytic myocarditis, often caused by viral infection.


Presentation of acute myocarditis is variable, ranging from subclinical disease to heart failure and patients can present with chest pain, shortness of breath, palpitations and fatigue. Most patients respond well to standard treatment, and the prognosis is good. However, it can progress to dilated cardiomyopathy and chronic heart failure, with evidence implicating it in 12% of sudden deaths in adults aged under 40.


Acute pericarditis can have a similar presentation to myocarditis, with chest pain and shortness of breath, and patients can also have concurrent myocardial involvement, known as myopericarditis. Treatment of pericarditis is aimed at the cause, with non-steroidal anti-inflammatory drugs (NSAIDs) the mainstay of therapy for viral, idiopathic and pericarditis associated with a systemic inflammatory disease. The long-term prognosis of pericarditis is good, but it can become recurrent and rarely patients can develop constrictive pericarditis.


Can myocarditis or pericarditis be caused by coronavirus (COVID-19) infection?

There have been a number of reports of cardiac involvement following COVID-19 infection in hospitalised patients, with approximately 18% of hospitalised patients suffering myocardial injury in the acute phase.


A recent preprint has provided some evidence of the risk of myocarditis following COVID-19 infection in individuals aged 12 to 19. After analysing mainly US electronic health records and adjusting for missed cases of COVID-19 and myocarditis, cases of myocarditis were estimated to be 450 per million COVID-19 cases for males aged 12 to 17, 601 cases for males aged 12 to 15 and 561 cases for males aged 16 to 19. For females aged 12 to 17, the myocarditis cases were estimated to be 213 per million COVID-19 cases, 235 per million cases for females aged 12 to 15 and 708 per million cases for females aged 16 to 19.


In a US study of 1,597 athletes with recent SARS-CoV-2 infection, 0.31% were diagnosed with myocarditis using a symptom-based screening strategy and 2.3% were diagnosed with clinical or subclinical myocarditis using cardiac magnetic resonance screening. Of those who had repeat imaging, 11 of 27 athletes had complete resolution of myocarditis signs (40.7% – range between studies, 4 to 10 weeks with median [interquartile range] of 8, 3.5 weeks.


In another study of college athletes in the US, of the 3,018 athletes who had tested positive for SARS-CoV-2, cardiac involvement was estimated at between 0.5% to 3.0%. During the 113-day follow-up period, there were no adverse cardiac events in those with myocarditis.


Is there an association of myocarditis or pericarditis following COVID-19 vaccination?

From analysis of UK and international data, there has been a signal of an increase of cases of myocarditis and pericarditis following vaccination with both Pfizer/BioNTech and Moderna vaccines. The Pfizer/BioNTech and Moderna vaccines have been used extensively in other countries, including the US and Israel.


In the US, 296 million doses of mRNA vaccines (Pfizer/BioNTech and Moderna) had been given by 11 June with 1,226 reports of myocarditis after vaccination (the US data analysis has included all cases of myocarditis, pericarditis and myopericarditis under myocarditis). In those with reported myocarditis, the median age was 26 years and the median time to onset was 3 days after the vaccination.


In Israel, between December 2020 and May 2021, there were 148 reports of myocarditis around the time of vaccination, with 5,401,150 individuals having received at least 1 dose of vaccine and 5,049,424 having received 2 doses. There have been higher incidences in younger males, and most cases reported after the second vaccination.


In the US, among those 1,194 individuals with myocarditis for which age was known, 687 were aged under 30 years, for those 1,212 individuals for which sex was known, 923 were male, and for those 1,094 individuals for which number of vaccine doses is known, 76% of cases developed myocarditis after dose 2. Reporting rates were 40.6 cases per million second doses of mRNA COVID-19 vaccines for males aged 12 to 29 years and 2.4 per million second doses for males aged 30 or older. For females their reported rates were 4.2 and 1.0 per million second doses in these age groups and the highest reporting rates were among males aged 12 to 17 and those aged 18 to 24 years. In Israel, 27 of the 148 cases occurred around receipt of the first vaccine dose and 121 occurred within 30 days after the second vaccine, with most cases in men aged 16 to 19 years.


Follow up of cases in the US, Israel and UK are ongoing to better understand the natural history and sequelae following the acute episode. To date, in the UK it appears that most individuals respond well to standard treatment.


The Centers for Disease Control and Prevention (CDC) further analysed US myocarditis data of in those aged under 30 years – 96% of cases were hospitalised but there were no deaths. However, 5 deaths have been reported in the European Economic Area in individuals of advanced age or with concomitant disease and so it is important that healthcare professionals are aware of this condition.


What is the UK data on myocarditis or pericarditis following COVID-19 vaccination?

Cases of myocarditis and pericarditis have been reported in the UK following vaccination with COVID-19 vaccines.


As of 28 July 2021, in the UK there were 149 reports of myocarditis and 129 reports of pericarditis following use of the Pfizer/BioNTech vaccine, 82 reports of myocarditis and 140 reports of pericarditis following use of the AstraZeneca (AZ) vaccine, and 25 reports of myocarditis and 22 reports of pericarditis following use of the Moderna vaccine.

The overall rates after both the first and second doses of Pfizer/BioNTech are 4.3 myocarditis cases per million doses and 3.8 pericarditis cases per million doses, for AZ the rate is 1.7 myocarditis cases per million doses and 3.0 pericarditis cases per million doses, and for Moderna the rate is 14.7 myocarditis cases per million doses and 13.0 pericarditis cases per million doses.


Up to 28 July 2021, 20.46 million first doses and 13.8 second doses of the Pfizer/BioNTech have been administered, 24.8 million first doses and 23.6 million second doses of the AZ vaccines and 1.3 million first doses of the Moderna vaccine have been administered. Given the extensive use of AZ vaccine in the UK programme, the cases reported after AZ vaccine are thought to reflect the expected background rate of these conditions.


What is the outcome of patients with myocarditis following COVID-19 vaccination?

The existing evidence base shows that most patients with myocarditis post vaccination respond well to standard treatment, and the prognosis of the myocarditis is good. However, it may have long-term consequences and studies are in progress to further understand the longer-term consequences with follow up at 3 months and 6 months.

In some cases of non-COVID-19 vaccine-related myocarditis, the disease can progress to dilated cardiomyopathy and chronic heart failure, with evidence implicating myocarditis in 12% of sudden deaths in adults aged under 40. Likewise, the long-term prognosis of pericarditis is good, but it can become recurrent and rarely patients may develop constrictive pericarditis.


Symptoms of myocarditis or pericarditis

Myocarditis and pericarditis present with new onset of chest pain, shortness of breath or feelings of having a fast-beating, fluttering, or pounding heart.

Anyone who develops these symptoms within 2 weeks of a COVID-19 vaccination should urgently seek medical assistance. Most of these cases are mild and recover in a short time period with standard treatment.


Reporting myocarditis and pericarditis following COVID-19 vaccination

It is very important that all suspected cases are reported to the Medicines and Healthcare products Regulatory Agency (MHRA) using the COVID-19 Yellow Card scheme.


Why are serum samples being requested if myocarditis is suspected after the first dose of vaccine?

The samples will be tested for antibodies to SARS-CoV-2 to determine whether the individual had previous COVID-19 infection and to determine the need for a second dose of vaccine.


Treatment

Most individuals respond well to standard treatment and recover quickly. Suspected cases should urgently seek medical assistance, and follow up as necessary.


If a patient has had myocarditis or pericarditis following the first COVID-19 vaccination, should they have a second dose?

If an individual develops myocarditis or pericarditis following COVID-19 vaccination they should be assessed by an appropriate clinician to determine whether it is likely to be vaccine related, and arrange for a blood sample to be taken, and sent to Colindale for testing (see reporting suspected cases).


The mechanism of action and risk of recurrence of myocarditis and pericarditis with a further dose of vaccine are being investigated, and the current advice is that an individual’s second dose should be deferred until further information becomes available, including the results of serological testing.


Should someone who has had myocarditis or pericarditis previously have a COVID-19 vaccination?

A history of myocarditis or pericarditis unrelated to COVID-19 vaccination is not a contraindication to receiving a COVID-19 vaccine.


The mechanism of action for causing these conditions following administration of a COVID-19 vaccine is being investigated and there is currently no evidence that people with a history of myocarditis or pericarditis are at increased risk of a recurrence following COVID-19 vaccination.

The risks and benefits of COVID-19 vaccination should be discussed with the patient so that they can make an informed decision.



References

  1. Lota and others. Epidemiological Trends and Outcomes of Acute Myocarditis in the National Health Service of England, 2019, Circulation, volume 140, Suppl 1 Abstract 11463.

  2. Golpour and others.Epidemiological Impact of Myocarditis, Journal of Clinical Medicine, 2021; 10, 603

  3. Blauwet L A and Cooper LT. Myocarditis, Progress in Cardiovascular Diseases, volume 52, issue 4, 2010

  4. Imazio M and Gaita F. Diagnosis and treatment of pericarditis, Heart, 2015 volume 101, issue 14

  5. Singer and others. Risk of Myocarditis from COVID-19 Infection in People Under Age 20: A Population-Based Analysis, medRxiv.

  6. Daniels and others. Prevalence of Clinical and Subclinical Myocarditis in Competitive Athletes With Recent SARS-CoV-2 Infection, JAMA Cardiology, 2021

  7. Moulson and others. SARS-CoV-2 Cardiac Involvement in Young Competitive Athletes, Circulation, 2021, volume 144, number 4.


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