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US warnings on rare heart inflammation after Pfizer or Moderna vaccines


Pfizer children


The US regulator is to add a warning of rare heart inflammation following Pfizer and Moderna jabs.

It follows a statement from the Centers for Disease Control that since April 2021 there had been more than a 1,000 reports through their adverse event reporting scheme of myocarditis and pericarditis after mRNA Covid-19 vaccination.

The events are rare given that more than 177 million people in the US have received at least one dose, the CDC said and most patients responded well to treatment and quickly felt better.

The MHRA told Pulse it is closely monitoring cases of myocarditis and pericarditis following some reports through the Yellow Card scheme after Pfizer, Astra Zeneca and Moderna vaccines, but stressed that cases were very rare.

Up to the 16th June, the MHRA has received 53 reports of myocarditis and 33 reports of pericarditis following use of the Pfizer/BioNTech vaccine, as well as one report each of viral pericarditis and streptococcal endocarditis. There have also been 42 reports of myocarditis and 77 reports of pericarditis following AZ vaccination, and three reports of myocarditis and one report of pericarditis following Moderna vaccination.

In the US, confirmed cases have mostly happened in male adolescents and young adults aged 16 years or older and more often after the second dose than the first of either Pfizer or Moderna vaccine.

It is typically reported within several days after vaccination, the CDC said and those affected can usually return to normal activities after symptoms improve.

Reports suggest the Food and Drug Administration will be adding the potential side effect to information leaflets about the vaccines.

Vaccine recipients are being made aware to be on the lookout for chest pain, shortness of breath or feeling a fast or fluttering heart beat in the week after vaccination.

The US is continuing to recommend vaccination for everyone aged 12 years and over.

The news comes as the UK is now giving only Pfizer and Moderna to people under 40 years of age, after the Oxford/AstraZeneca vaccine was linked to rare blood clots.

A spokesperson for the MHRA told Pulse: ‘We will continue to closely monitor these events reported in the UK and internationally. These reports are very rare, and the events are typically mild with individuals usually recovering within a short time with usual treatment and rest. People should come forward for their first and second vaccination when invited to do so, unless advised otherwise.

‘It is important that anyone who experiences new onset of symptoms such as chest pain, shortness of breath or feelings of having a fast-beating, fluttering, or pounding heart seeks medical attention.’