"Myocarditis removed from the NHS website", reads a tweet that published the false claim on August 22 and was shared more than 900 times.
"Wow we're (sic) too many cases appearing too quickly following a medical experiment on humanity".
Myocarditis -- inflammation of the heart muscle -- can cause chest pain, shortness of breath, and rapid or irregular heart rhythms.
According to the US Centers for Disease Control (CDC), myocarditis after vaccination with an mRNA Covid-19 vaccine is rarely reported.
It says on its website that reported cases mainly occur in adolescents and young adult males within several days of the vaccination, and most patients who receive care recover quickly.
Guidance from the UK Health Security Agency (UKHSA) in March also describes myocarditis as a "very rare condition following vaccination".
It adds that patients typically recover fully without medical treatment.
Similar claims that the NHS removed information about myocarditis were also shared on Facebook and elsewhere on Twitter.
However, the claim is false.
"We added 'Heart inflammation' as a potential rare side effect on the page 'Coronavirus (COVID-19) vaccines side effects and safety' in June 2021," an NHS spokesperson told AFP on August 31.
"In October 2021 we updated the references to read 'Heart inflammation (myocarditis)', and this convention has remained in place since. We continue to publish information in line with the latest clinical guidance."
The material was still available on the NHS website as of September 2, but a search for "myocarditis" using the website's search function gives no results.
Below is a screenshot of the information about myocarditis on the NHS website:
The page states it was last reviewed on April 28 and will be reviewed again on October 28.
AFP has previously debunked misleading claims about the number of vaccinated people developing myocarditis and the risk of developing the condition after vaccination.