On Tuesday night, the Health Ministry released data about what was defined as a “likely” link between the coronavirus vaccine and myocarditis – an inflammation of the heart.
All coronavirus vaccines – including the one created by Pfizer which has been used in Israel almost exclusively – have been fast-tracked for approval in light of the deadliness of a pandemic and have received an emergency authorization.
While the vast majority of the medical community have staunchly supported the vaccine, the general public has been at times hesitant. Many countries have seen their anti-vax populations growing dramatically, often influenced by a flux of fake news and conspiracy theories.
If not put in the proper context, the ministry’s announcement, while fulfilling the praiseworthy commitment to full transparency to the public, risks being interpreted in the wrong way.
“First of all, in order to really assess whether there is a link between the vaccine and the myocarditis cases, we need much more than what the ministry has communicated,” Prof. Eyal Leshem, the director of the Center for Travel Medicine and Tropical Diseases at Sheba Medical Center, said. “Among other things, we need to know how much time passed between the inoculation and the event, we need a case control group… Evaluating a possible adverse effect of a vaccine is very challenging.”
“Proper analysis of the information requires time, and it could also be that the effect is so rare that Israel will never have enough mass to provide proper data,” he added. “In the United States, where tens of millions of doses have been administered, they have not seen clear proof of this.”
Myocarditis is an inflammation of the hearth muscle which can be caused by a viral infection, but also appears as a reaction to a medication.
The symptoms include pain in the chest, arrhythmias and shortness of breath.
The ministry’s report showed that out of the 275 myocarditis cases reported in Israel between December and May – since the beginning of the vaccination campaign – 148 occurred in the aftermath of a vaccination, most of them after the second dose. More than 95% were considered mild. Most of the patients were discharged from the hospital within four days. Many of the cases were reported among men aged 16-30.
According to Leshem, the cases could still be part of the normal occurrence of the inflammation. Unless a thorough control is done comparing the data from the vaccinated population with that from the normal population, it will not be possible to show that there is a connection.
“This is not proof, it is just a signal that the phenomenon has to be investigated,” he said.
“Even if the connection was demonstrated, the vast majority of the cases were mild and self resolved and this is the most important part,” he remarked. “We know that every vaccine can have side effects. It could be that one in several thousands of doses led to a mild inflammation of the heart. If we were to find out that one in 10,000 doses can cause a mild myocarditis, this could be considered an acceptable adverse event rate.”
Leshem stressed that after the vaccine people should refrain from intense physical activity which can favor the occurrence of these events.
For the professor, the key message is for the public to receive complete data but for it to be interpreted by experts “because it can look scary.”
“In reality, everyone around us got vaccinated and with millions and millions of doses there has not been any substantial rate of adverse events, so there is no reason to think we are missing anything that is common,” he said. “As for very rare adverse events, there is no medical treatment that does not have them, including the most common medications like paracetamol.”
“Even when we cross the street, we can be hit by a car,” he concluded. “Our Health Ministry is very cautious and has some of the best experts in the world. People should follow its recommendations.”