In 1998, people could have said the same thing about the varicella vaccine compared to MMR, DTP, and Tdap. Around the same time period, they had started administering the rotavirus vaccine and subsequently found an association with incidence of intussusception and stopped administering it. Rotashield was subsequently withdrawn from the market. After 8 years, other rotavaccine formulations were approved and are now part of the routine childhood immunization schedule.
What happened with Rotashield did not happen with the Pfizer and Moderna formulations of the COVID-19 vaccine and subsequent boosters.
> Long-term study results for COVID vaccination simply don't exist for obvious reasons; it's only been about three years since the vaccine was first publicly administered.
This is the case for all vaccines when they first start being used.
> Countries like Sweden recommend against vaccinating children 5-11 because they think the benefits don't outweigh the risks.
Which vaccine are you referring to?
> It's funny, but the UK doesn't have varicella in the vaccine schedule for children for fear it will lead to a risk of chickenpox and shingles in adults[1], which can be more severe.
The varicella vaccine has been routinely administered to children since the late 90s in the US. If it lead to an increase in incidence of chickenpox in adulthood, then we would have heard about it by now. As for shingles, it remains to be seen, but this condition is not uncommon in the older population who were infected with chickenpox in their childhood.
We wouldn't continue recommending the COVID-19 boosters if there was a real problem associated with the vaccine that was worse than the morbidity/mortality statistics from the infection itself.