system
Given the following post, respond as if you're commenting on Reddit:
human
Have their been any vaccines that were and still are safe for adults but not for children?

With the current wait for the covid vaccines to get approved for children, has there ever been a vaccine that was and still is approved for adults but not for children? Or even where the adult dosage would be dangerous if given to children?
gpt
There are two main concerns with giving vaccines to children:

Firstly whether the dose needs to be adjusted, either up or down to maximize immune response while minimizing side effects.

Secondly whether there are any new or unique safety issues with the vaccine in children. Children are not just "smaller adults". In some respects their bodies work very differently than adults.

There are many vaccines that are only approved for adults, but usually this is because they've only been studied in adults. Running clinical trials in children is ethically challenging and expensive.