Undesirable side effects of a vaccine are closely monitored not only during clinical testing but also after its final approval, when it has already been used largely.
It turned out that the development process of a vaccine can be significantly accelerated without violating safety. Even so, however, the vaccine had to successfully pass all the clinical trial phases (I, II, III) - like had any vaccine in the past. Hundreds of volunteers in the Phase II as well as thousands in the Phase III got the vaccine administered since mid-2020 - with another thousands of vaccinated patients joining the crowd now. Apart from few known reactions (headache, muscular pain, tiredness etc.), no significant side effects have until now been observed.
Nobody knows what will come in 10 years, however, the farther we are from the starting point of the vaccination, the more probable is that this will stay so.
A lot of people might connect their diseases or health issues with the COVID vaccine - since the majority of the population will have got it at that time. If two phenomena appear directly after each other or if two variables are just related to each other, we cannot consider the one being the cause and the other the consequence. Remember the furor triggered by connecting the MMR vaccine and the development of autism in children? No relation could be proven - except that autism is usually diagnosed and the first dose of the MMR vaccine usually administered when the patient is a child.
In medicine, we often use risk-benefit assessment. We should know that the benefits of a vaccine that will protect us, and with us millions of other people, from a serious disease with potentially permanent consequences, by far exceed the - even already now minimal and with time further decreasing - risk of any unspecified long-time side effects, as the fear of them accompanied every new vaccine in the human history. Until now, vaccinations turned out only as a prove of their great importance in health protection and their ability to save a number of human lives - and no long-time negative consequences.
Original Czech text author: MUDr. Petr Smejkal, Ph.D.