The news sounds frightening: the risk of a vascular occlusion in the retina of the eye has doubled after the mRNA vaccination, and one could become blind. Many who hear this are now wondering if it was right for them to get vaccinated against Covid-19. And those who have always been against the “gene broth” feel vindicated. The “eye attack” is making waves in the social media, pushed up by the Worldwhich moves close to swagger and lateral thinking.
The message is a prime example of unfair medical journalism. Because what really happened? In fact there is in a journal called npj vaccines a study, in which 2.2 times as many people with retinal vascular occlusion were found among vaccinated individuals than among unvaccinated individuals. Only: The authors themselves come to the conclusion that their study in no way proves the connection with the vaccination and that the risk of vascular occlusion in the eye is “extremely low” in any case.
This is precisely the point that distinguishes good risk communication from bad. It is important to consider: How well documented is a possible risk? And above all: How high is it anyway?
No relative probabilities, but absolute numbers are decisive
A “doubling of the risk” sounds frightening at first. However, as a patient, a doubling of a tiny risk can be of little concern to you. Serious experts therefore do not use relative probabilities, but give absolute numbers. They are as follows: In this study, 752 of 740,000 people who were not vaccinated suffered a vascular occlusion in the eye, among those who were vaccinated it was 1506 of 740,000. Among the almost 100,000 people who were vaccinated twice with Biontech, 116 people had a vascular occlusion in their eye , among the same number of unvaccinated people there were 107, with Moderna there were 106 versus 75, but among only around 50,000 people in both groups. So the mRNA vaccines performed even better than others because there were not nearly twice as many cases among those vaccinated with these vaccines as among unvaccinated people. In addition, there were differences between the groups that limit the direct comparison: among the vaccinated there were more smokers, more had diabetes, were overweight and heart problems – all risk factors for vascular occlusions, also in the eye.
For all these reasons, the authors explicitly recommend vaccination. Despite all this, she writes World, a side effect was “fixed”, “the origin of the news cannot be more serious”. In fact, this claim could hardly be more dubious.