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Updated information on rare Covid-19 vaccine side effects issued

heart inflammation

The Government has issued more detailed guidance for health professionals on some rare side effects associated with Covid-19 vaccines. 

It includes the latest data on rates of myocarditis and pericarditis that have been reported with Pfizer/BioNTech and Moderna vaccines as well as an update on what is known about Guillain-Barre syndrome following Covid vaccination

The information from Public Health England (PHE) includes figures on vaccination and side effects from US, Israeli and UK databases and notes the rate after first and second doses are 4.3 myocarditis cases per million doses and 3.8 pericarditis cases per million doses for Pfizer/BioNTech and 14.7 myocarditis cases per million doses and 13.0 pericarditis cases per million doses for Moderna. 

It also points out that there have also been reports after AstraZeneca vaccine with a rate of 1.7 myocarditis cases per million doses and 3.0 pericarditis cases per million doses but that these likely reflect the expected background rate of these conditions. 

A history myocarditis or pericarditis unrelated to Covid-19 vaccination is not a contraindication to receiving a vaccine, it advises. 

As of 1 September, the MHRA has received 238 reports of myocarditis and 189 reports of pericarditis following use of the Pfizer/BioNTech vaccine and 101 reports of myocarditis and 158 reports of pericarditis for AstraZeneca vaccine.

The guidance urges doctors to report any suspected case to the MHRA through the Yellow Card scheme as well as collecting serum samples to send to PHE to test for antibodies to inform decisions around future vaccination in that individual. 

Investigations are ongoing to assess with reports of Guillain-Barre syndrome after Covid vaccination are related to the jab or would have been expected to occur anyway, the PHE guidance says. 

As of the start of this month, in the UK there have been 397 reports of Guillain-Barre syndrome following AstraZeneca (AZ) vaccination and 23 reports of Miller Fisher syndrome in the UK. 

The rates are consistent with what has been seen after other viral mass vaccination campaigns, PHE said. 

This compares with 42 reports after Pfizer/BioNTech vaccination and two after Moderna – lower than would have been expected by chance. 

No causal link has been proven between Covid-19 vaccination and Guillain-Barre syndrome so anyone who has previously been diagnosed with it is still recommended to be vaccinated. Anyone who had it after the first dose should still get their second jab, PHE advised.