A few things to note:

- Child mortality is the lowest it ever has been, historically.
- Leukemia in kids is very rare. It is the most common solely by other types of cancer being even more rare. It's not "common" by any means.
- Most cases of leukemia, as with other cancers, appear in adults, especially older ones.
- Formaldehyde is not an ingredient in vaccines, it is used as a sterilizing agent during production. What's in vaccines are leftover trace amounts.
- Every single cell of every living organism contains formaldehyde naturally, as it's part of the cell's metabolism process.
- The trace amounts of formaldehyde in vaccines are less than what your body contains from just existing.

In short: This post is pure fearmongering.