A new side effect linked to the Pfizer and Moderna Covid-19 vaccien jabs has been added to the official list by the UK medicines watchdog.

As the vaccine programme continues to roll out across the country, the latest Covid vaccine July updates, “extremely rare reports of myocarditis and pericarditis” have been added to the guidance.

Myocarditis refers to inflammation of the heart muscle, and pericarditis is inflammation of the outer lining of the heart.

‘Seek immediate medical attention’

The Commission on Human Medicines (CHM), the MHRA and the Government’s independent expert advisory body, has conducted a thorough review of suspected adverse reaction reports of myocarditis and pericarditis following Covid-19 vaccination.

After considering the available data, the CHM has advised that healthcare professionals should be alert to signs and symptoms of myocarditis and pericarditis.

Vaccinated individuals are advised to seek “immediate medical attention should they experience a new onset of chest pain, shortness of breath, palpitations or symptoms or arrhythmia”.

The Government states that myocarditis and pericarditis happens “very rarely in the general population”.

The MHRA will “continue to closely monitor cases of myocarditis and pericarditis with all of the currently authorised Covid-19 vaccines”.

‘Extremely rare’

Dr June Raine, MHRA Chief Executive, said: “We have carefully reviewed reports of suspected adverse reactions involving types of heart inflammation known as myocarditis and pericarditis.

"We have concluded that the Covid-19 vaccines made by Pfizer/BioNTech and Moderna may be linked with a small increase in the risk of these very rare conditions.

"The cases tended to be mild and the vast majority recovered with simple treatment and rest."

The Government said: “These reports are extremely rare, and the events are typically mild with individuals usually recovering within a short time with standard treatment and rest.

“People should come forward for their first and second vaccination when invited to do so, unless advised otherwise.”

Reports of myocarditis and pericarditis

As of 23 June 2021, the MHRA has received 60 reports of myocarditis, and 42 reports of pericarditis following the use of the Pfizer vaccine.

There have been five reports of myocarditis and two reports of pericarditis following use of the Moderna vaccine up to the same date.

For the AstraZeneca vaccine, there have been 51 reports of myocarditis and 89 reports of pericarditis following vaccination up to and including 23 June 2021.

For context, as of 23 June 2021, an estimated 18 million first doses, and around 11 million doses, of the Pfizer vaccine has been administered. Approximately 0.88 million first doses of the Moderna vaccine have also been administered.

The Government says that there has been a “consistent pattern of cases occurring more frequently in young males and shortly after the second dose of the vaccine”.