Guidance

Information for healthcare professionals on myocarditis and pericarditis following COVID-19 vaccination

Updated 21 March 2022

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 a pre-COVID-19 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 was 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?

It is now recognised that COVID-19 infection can lead to myocarditis or pericarditis and in one retrospective study, 5% of patients developed new onset myocarditis and 1.5% pericarditis within a 6 month period following COVID-19 infection .

Professional athletes are an atypical group but 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%).

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?

Many studies have now shown that there is an increased risk of myocarditis following vaccination with an mRNA vaccine, especially in young men under the age of 40. Although the relative risk differs in different countries probably related to a combination of the genetic background, the different vaccination schedules and how the cases are defined, the risks are higher in subsequent doses compared with the first dose. Many of the studies have only limited follow up, and the long-term consequences of vaccine-associated myocarditis is unclear.

In one of the largest studies published to date on the Israeli experience, over 2 million individuals were assessed. The estimated incidence of myocarditis was 2 per 100,000 individuals, with the highest reported rate in males aged 16 to 29. 76% were classified as mild and 22% intermediate. One case developed cardiogenic shock, and one was readmitted to hospital during the follow up period. Fourteen patients had left ventricular dysfunction on Echocardiogram with 10 of these still having dysfunction at time of discharge (subsequent follow up indicated that 5 of these individuals had normal heart function).

The Centers for Disease Control and Prevention (CDC) further analysed US myocarditis data in those aged under 30 years – 96% of cases reported between 1 May and 11 June 2021 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 as well as one death in Israel between December 2020 and May 2021, and so it is important that healthcare professionals are aware of this condition and the advice regarding management of suspected cases following vaccination.

Clinical guidance on the investigation and management of suspected cases of myocarditis following COVID-19 vaccination has been developed and recently updated by an expert working group including representation from paediatric cardiologists, the Royal College of Emergency Medicine and Royal College of General Practitioners.

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

All suspected cases of myocarditis and pericarditis in the UK following vaccination with COVID-19 vaccines should be reported to MHRA (link) who regularly publish the number of reported numbers.

As of 2 March 2022, in the UK there were 739 reports of myocarditis and 507 reports of pericarditis following use of the Pfizer/BioNTech vaccine, 221 reports of myocarditis and 216 reports of pericarditis following use of the AstraZeneca (AZ) vaccine, and 212 reports of myocarditis and 119 reports of pericarditis following use of the Moderna vaccine to the Medicines and Healthcare products Regulatory Agency (MHRA). Many of these are self-reports, and have not been confirmed by medical adjudication.

The reporting rate by age group and vaccine product is shown in table 1 below.

Table 1: Reporting rates per million doses for UK adverse drug reaction (ADR) reports of suspected myocarditis and pericarditis associated with COVID-19 vaccines, by patient age and dose, up to and including data to 2 March 2022.

Age range (years)	Pfizer/BioN Tech 1st or unknown dose	Pfizer/BioN Tech 2nd dose	Pfizer/BioN Tech 3rd or booster dose	Moderna vaccine 1st or unknown dose	Moderna vaccine 2nd dose	Moderna vaccine 3rd or booster dose	AstraZenica vaccine 1st or unknown dose	AstraZenica vaccine 2nd dose
Under 18	14	12	Not applicable**	Not applicable**	Not applicable**	Not applicable**	Not applicable**	Not applicable**
18 to 29	24	28	15	58	70	20	10	16
30 to 39	22	25	13	55	55	20	13	12
40 to 49	19	19	13	54	28	14	12	9
50 to 59	8	16	7	Not calculated*	Not calculated*	7	8	7
60 to 69	8	13	6	Not calculated*	Not applicable**	7	7	6
70 and over	4	5	4	Not applicable**	Not applicable**	2	4	4

*There is currently insufficient data to calculate a reliable estimate of the reporting rate in the UK due to the relatively limited exposure and small numbers of suspected reports in these individuals.

** There have been no reports of suspected heart inflammation events received for individuals in these age groups.

Source: MHRA summary of yellow card reporting.

The latest information on suspected cases can be found in the MHRA’s weekly summary of yellow card reporting.

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 10 days 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 MHRA using the COVID-19 Yellow Card scheme.

Treatment and guidance

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

Specific guidance on treatment and referral for primary care and emergency care clinicians is available. This guidance was developed by a multidisciplinary team of clinicians and royal colleges and is endorsed by the Royal College of Emergency Medicine and Royal College of GPs.

If a patient has had myocarditis or pericarditis following a COVID-19 vaccination, should they have subsequent doses, including second and booster doses?

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.

Patients who did not require referral to hospital on initial presentation or who had normal investigations do not require follow-up. Patients who have been referred to cardiology and diagnosed with confirmed myocarditis following COVID-19 vaccination should be reviewed by their cardiologist 8 weeks after their diagnosis to assess their eligibility for further vaccination.

If there is no evidence of ongoing myocarditis, they can be offered vaccination with the Pfizer (Cominarty) vaccine from 12 weeks after their last dose if further doses are due.

If there is evidence of ongoing effects of acute or subacute myocarditis, then an individual risk benefit assessment should be undertaken in consultation with the patient or their parents or guardians prior to offering further doses of COVID-19 vaccine.

In light of the higher reported rates of myocarditis following the Moderna vaccine (see table 1), Pfizer/BioNTech is preferred over Moderna.

AstraZeneca should not be offered to those who have not previously received an AZ vaccine given the risk (albeit rare) of thrombosis and thrombocytopaenia syndrome following a first dose of an adenovirus vector vaccine.

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 unrelated to COVID-19 infection or vaccination 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. Assessment of the risk benefit for an individual should consider age, comorbidities, previous COVID-19 infection and current levels of COVID-19 transmission.

If a patient has had myocarditis or pericarditis following COVID-19 infection, should they have COVID-19 vaccination?

Individuals who have had an episode of myocarditis following COVID-19 infection should be assessed by an appropriate clinician and if there is no evidence of ongoing myocarditis the risks and benefits of COVID-19 vaccination should be discussed with the patient or guardians so that they can make an informed decision.

Assessment of the risk benefit for an individual should consider age, comorbidities, the previous COVID-19 infection and current levels of COVID-19 transmission. Vaccination with the Pfizer (Cominarty) vaccine can be offered from 12 weeks after their recovery.

AstraZeneca should not be offered to those who have not previously received an AZ vaccine given the risk (albeit rare) of thrombosis and thrombocytopaenia syndrome following a first dose of an adenovirus vector vaccine.

Should individuals refrain from exercising following vaccination?

If an individual feels well after receiving their COVID-19 vaccination then there is no need to pre-emptively restrict physical activity post vaccination and individuals can continue with their pre-existing level of physical activity.

In the unlikely event that they experience chest pain, palpitations, unexpected shortness of breath, or fainting, then they should seek medical attention.

Such individuals should be investigated and managed according to the clinical management guidelines. This advice applies to both adults and children. Strenuous physical activity should be avoided until symptoms improve. If an individual has been diagnosed with myocarditis or pericarditis, advice on exercise should be given by a qualified health care professional (for example cardiologist, sports cardiologist or sports medicine physician) and should follow clinical guidelines on when to resume activity or competitive sports.

These recommendations are based on the expert opinion of the working group informed by data from Yellow Card reporting data and other published data.