This goes for any campaign, content or research you ever run.
It is often easy to receive content and charge ahead without thanking your respondents for taking part. The problem is that respondents could feel unappreciated, detached, unsure if they are still needed - all of which can reflect badly on your brand, or yourself.
ALWAYS SAY THANK YOU.
If you end up publishing content, share it back with the individuals involved. All you can do is inspire greater engagement, word-of-mouth and involvement in future campaigns.