Decisions relative to vaccination of any kind are made using a risk/benefit analysis, which is a fundamental aspect of a process called “informed consent”. Many parents and most children do not do this analysis prior to being injected with a medicine that can’t be removed later if they learn new information about the medicine.
Traditionally, vaccines have been designed and tested over many years to be sure they are safe and effective at preventing a viral or bacterial infection. Prevention of disease is their main feature. Vaccines developed in record short intervals against the SARS-CoV-2 virus do not have long term safety studies. The children’s version had only 3 months of data for children ages 5-12, and these trials were performed with only a few thousand participants. Furthermore, they do not prevent infection. Instead, the main feature is to reduce more severe symptoms and limit spread. Both of these are virtually insignificant with young children.
The short answer to the question is that there appears to be few, if any, benefits to vaccination of young children. The small number who experience more severe symptoms usually have significant comorbidities unrelated to Covid. This is described as ‘sick with Covid’ rather than ‘sick because of Covid’. An excellent study to demonstrate this is the Swedish school study published in the New England Journal of Medicine. This is a superb study because Sweden never did shut down schools and they take excellent records. Note, there was not one recorded death (no severe symptoms) due to Covid in the study and teachers did not get Covid any more often than other types of workers their age. (Children aren’t spreaders)
https://www.nejm.org/doi/full/10.1056/NEJMc2026670
Now let us consider the evidence of risk. Since vaccination of very young children has not started yet, we can only measure risk of other ages and apply it to the 5-12 year olds. Needless to say that younger children have the same potential risks as older children and adults, if not more. Many of these are life-altering, including myocarditis, especially in boys.
https://www.medrxiv.org/content/10.1101/2021.08.30.21262866v1
Why are children less likely to develop more significant symptoms of COVID-19? Children have very active innate immune systems looking to be stimulated and develop more specific adaptive responses to pathogens, such as the development of antibodies. With respect to SARS-CoV-2, however, the spike protein needs to bind to specific receptors on the surface of the cell before the virus can enter. Children have much lower levels of the angiotensin converting enzyme 2 (ACE-2) protein, which permits the entry of the virus. This step is necessary for viral replication, so it is severely slowed down in children, and this provides more time for the robust innate immune defense in children to defeat the virus before it causes severe disease. Enough does enter to allow the child’s body to develop an antibody response and a natural immunity that will be with them for life. The key is that children do not develop high viral loads to facilitate spread.
The bottom line is that there are significant risks with few to no benefits from vaccinating children from ages 5-12. It may even rob them of an opportunity for lifelong natural immunity, and present health risks such as inflammation and possibly autoimmune diseases.