Do you need to worry about mercury in the first place? Researchers battle back and forth over this issue. We’ve known for decades that mercury is toxic to the brain and body tissues. But whether or not the amount in vaccines is enough to cause damage is still up in the air. Some research shows there is enough evidence of harm; other studies have found there is not enough proof that the mercury in vaccines is dangerous. However, no study has yet to prove for certain that this mercury is safe.
Because we just don’t know yet for sure, in my opinion it’s better to just skip the flu shot (unless you have a chronic medical condition that makes the flu risky for you) if you can’t find one without mercury.