Israel is investigating a small number of cases of heart inflammation among people who have been vaccinated with the Pfizer coronavirus jab.
Health officials said 62 out of 5million people given the American-made vaccine developed myocarditis, the medical name for swelling in the heart.
Pfizer said it has not seen a higher rate of the condition than would normally be expected in the population, but experts are investigating in order to be sure.
Early analysis of the country’s rollout suggests the condition is occurring more frequently in men under 30 and in people given both doses.
The condition often has no symptoms and heals on its own, but in some people it can cause more serious problems including heart failure or weakening of the heart.
Viral infection is a known cause of the condition and chemicals released by the immune system when it is fighting a virus can trigger the swelling.
Israel’s pandemic response coordinator, Dr Nachman Ash, said two of the 62 patients in the records had died while the rest made full recoveries.
Statistics suggest around 3million people per year are diagnosed with cardiomyopathy worldwide, but many more are thought to have it but never know.
The concerns come after a storm about possible links between the AstraZeneca and Johnson & Johnson vaccines and bloot clots culminated in many countries refusing to give the AZ jab to young people.
An Israeli military paramedic prepares a Pfizer COVID-19 vaccine, to be administered to elderly people at a medical center in Ashdod, southern Israel. January 7, 2021
Dr Ash said that a study showed ‘tens of incidents’ of myocarditis occurring among more than five million vaccinated people, primarily after the second dose.
He said it was unclear whether this was unusually high or whether it was connected to the vaccine.
WHAT IS MYOCARDITIS?
Myocarditis is an inflammation of the heart muscle. There are no specific causes of the condition but it is usually triggered by a virus.
Some of the most common infections which cause myocarditis, are those called adenovirus and Coxsackie B.
It can be caused by the common cold, hepatitis B and C, and herpes simplex virus.
The most common symptoms of the condition include chest pain, a fever, a fast heartbeat, tiredness and shortness of breath.
If the inflammation damages the heart muscle or the fibres that conduct electrical pulses to the heart, complications can develop.
They can develop quickly, and include sudden loss of consciousness, an abnormally fast, slow or irregular heartbeat.
In very severe cases the condition is fatal, causing heart failure or sudden death. The inflammation enlarges the heart and creates scar tissue, forcing it to work harder and therefore making it weaker.
In most cases of viral myocarditis, the illness goes away and there are no complications.
But in rare cases when inflammation is severe, there can be damage to the heart which needs monitoring and possibly a heart transplant.
Myocarditis can reoccur, but there is no known way to prevent this. The risk of recurrence is low, around 10 to 15 per cent, according to Myocarditis Foundation.
It is difficult to gauge the prevalence of myocarditis because there is no widely available test for it.
In 2010, approximately 400,000 people died of heart muscle disease – cardiomyopathy that includes myocarditis – worldwide.
Expert consensus opinion estimates that up to 40 per cent of dilated cardiomyopathy results from myocarditis, according to the National Organisation for Rare Disorders.
Among all people who had received the vaccine the condition occurred at a rate of one in 100,000 people, but for men aged between 18 and 30 it was one in 20,000 – five times higher, Bloomberg reported.
Despite this, there is no proof the vaccine is causing it to happen.
Dr Ash said: ‘The Health Ministry is currently examining whether there is an excess in morbidity [disease rate] and whether it can be attributed to the vaccines.’
He described the issue as a ‘question mark’ in a radio interview.
Determining a link, he said, would be difficult because myocarditis, a condition that often goes away without complications, can be caused by a variety of viruses and a similar number of cases were reported in previous years.
Pfizer told Reuters it was in regular contact with Israel’s Health Ministry while it reviewed data on its vaccine.
The company said it ‘is aware of the Israeli observations of myocarditis that occurred predominantly in a population of young men who received the Pfizer-BioNTech Covid-19 vaccine’.
‘Adverse events are regularly and thoroughly reviewed and we have not observed a higher rate of myocarditis than what would be expected in the general population. A causal link to the vaccine has not been established,’ the company said.
‘There is no evidence at this time to conclude that myocarditis is a risk associated with the use of Pfizer/BNT Covid-19 vaccine.’
Myocarditis is a condition in which the heart muscle becomes swollen, which affects its ability to pump blood, usually making it weaker.
It is most often triggered by another infection, such as a viral flu infection – suggesting coronavirus could cause it – or bacterial, parasite or fungal infection.
Scientists believe the reason infection can trigger the condition is that it is caused by chemicals called cytokines, which are released by the immune system when it’s in attack mode.
These can then lead to changes inside the body which result in the swelling in the heart.
Generally, when the original illness is over and the immune system goes back to normal, the myocarditis will fade away on its own.
But in some people it can trigger severe or even deadly complications such as heart failure, heart attack, stroke or sudden cardiac arrest.
Israel has been a world leader in its vaccination rollout, with close to 60 per cent of its 9.3million population having received the Pfizer vaccine.
Its nationwide database has already showed the vaccine to be highly effective in preventing the symptoms and severe illness associated with Covid-19.
Since January, shortly after the vaccine campaign began, daily infections dropped from a peak of more than 10,000 to just 129 before the weekend.
Nadav Davidovitch, director of the school of public health at Israel’s Ben Gurion University, said that even if a correlation between the myocarditis cases and the vaccine were established, it did not appear to be serious enough to stop administering the vaccine.
‘It’s a situation that should be looked into, and we need to wait for a final report, but in an interim analysis it seems the risk of getting sick from Covid-19 is much higher than from the vaccine’s adverse events, and the risk of myocarditis following the vaccine is low and temporary,’ he said.
BLOOD CLOTS MORE LIKELY AFTER COVID THAN AFTER VACCINE
People are up to 10 times more likely to develop a brain blood clot after catching Covid than after getting a vaccine, a study found.
Cerebral venous sinus thombrosis is the condition that has spooked regulators by appearing in recipients of the AstraZeneca or Johnson & Johnson jabs.
But Oxford University researchers claim the risk of developing the complication is significantly higher after getting coronavirus than it is after receiving any of the Covid jabs.
The benefits of getting vaccinated are far higher than the risks, they insist, because the chance of getting a clot is still vanishingly rare and mass vaccination will protect millions of people – both those who get the jabs and the people around them.
The scientists studied data from the US to work out how often people were diagnosed with CVST after testing positive for coronavirus.
They estimated the rate was 39 cases per million people – 0.0039 per cent, or one in every 25,641.
The rate for people who had Pfizer or Moderna’s vaccine was about four in a million – 0.00039 per cent or one in 250,000.
And, based on European data, they said the risk after AstraZeneca’s jab appeared to be roughly five in a million – 0.0005 per cent or one in 200,000.
‘The key message is that the risk of this particular event is actually much lower than if you get Covid or someone else gets Covid,’ said Dr John Geddes of the university’s biomedical research centre.
The study came after another Oxford professor not involved with the research, Sir John Bell, said that the blood clot risk after vaccination was ‘trivial’.
The Oxford study’s calculations suggested the rate of CVST is 39 in a million among people who have tested positive for Covid-19, compared to between four and five per million after vaccination