Avoiding awk injection

I have a script which reads an VCS log, converts that to latex, and then uses awk to replace keyword @COMMITS@ in a template with the text:

untagged=$(get-commit-messages "$server" "$rev")
IFS=$'\n' untagged=( $untagged )  # Tokenize based on newlines
for commit in "${untagged[@]}"; do
  tex+="\\\nui{"                  # Wrap each commit in a custom command
  tex+=$(echo "$commit" | pandoc -t latex --wrap=none)
  tex+="}
"
done

awk -v r="$tex" '{gsub(/@COMMITS@/,r)}1' template

Since commit messages are really just text, I use pandoc -t latex to ensure everything is escaped properly for the latex parser. My problem is that the awk parser un-escapes these. If I find a _ in a commit message, pandoc will replace that with \_, but then awk will convert it back and give a warning:

awk: warning: escape sequence \_' treated as plain _'

That will cause the latex parser to fail. Is there a way for me to prevent awk from un-escaping stuff? If not I'll look for a non-awk solution for text-replacement.