The Medicines and Healthcare products Regulatory Agency (MHRA) delivered its findings following a statement by the European Medicines Agency (EMA), which said that inflammatory heart conditions (myocarditis and pericarditis) could occur “in very rare cases” for those who received the two vaccines.
The MHRA said it had reached its conclusion after a “thorough review” of data in both the UK and internationally and stressed that the benefits from either vaccine “greatly outweigh” any potential risks.
Myocarditis involves the inflammation of the heart muscle itself, while pericarditis involves the inflammation of the fluid-filled sac the heart sits in.
Symptoms of heart inflammation include chest pain, shortness of breath, palpitations and an irregular heartbeat.
Analysis by the EMA found 145 cases of myocarditis and 138 cases of pericarditis in 177 million doses of Pfizer given in the European Economic Area (EEA).
It also found 19 cases of myocarditis and 19 cases of pericarditis out of 20 million doses of Moderna given in the EEA.
The review found that five people had died as a result, but all has suffered from existing health conditions or were elderly.
Most cases are thought to be within 14 days of vaccination. While the risk is very rare, it is more likely to develop in young people, the BBC reported.
There was no link to heart inflammation conditions found for either the Oxford-AstraZeneca or Janssen vaccines.
Dr June Raine, CEO of the MHRA said: “The MHRA has conducted a thorough review of the data, both in UK and international sources, and has identified that there may be an extremely rare risk of myocarditis and pericarditis following vaccination with the Moderna and Pfizer Covid-19 vaccines.
“Reports of suspected myocarditis and pericarditis post-vaccination with Pfizer/BioNTech and Moderna typically describe mild symptoms and recovery, following usual treatment and rest.
“The benefits of these vaccines in protecting against hospitalisation and death from Covid-19 greatly outweigh any potential risks, and people are encouraged to continue to come forward for their first and second vaccination when invited to do so.”
The EMA also said the benefits of all authorised coronavirus vaccines “continue to outweigh their risks.”
But it added that people should seek immediate medical attention if patients experienced symptoms of breathlessness, a forceful or irregular heartbeat and chest pain.
“The chance of these conditions occurring is very low, but you should be aware of the symptoms so that you can get prompt medical treatment to help recovery and avoid complications,” the agency said.
Similar concerns were previously voiced over a link between blood clots and the Oxford/AstraZeneca vaccine, but the UK’s Joint Committee on Vaccination and Immunisation (JCVI) said this is an “extremely small risk.
Up to 8 June, 65 percent of the UK population have received two doses of a coronavirus vaccine and 86.8 percent have had one.
Roughly 18 million first and 11 million second doses of the Pfizer vaccine have been given out in the UK, while around 880,000 Moderna first doses have been given.
Additional reporting by Press Association