In July 2021, we launched an online user study on digital COVID-19 immunity certificates in the Republic of Ireland. The study design included an initial online screening survey with a random prize draw among those who completed it (20 euro Amazon voucher), which attracted a bot attack with a massive number of fraudulent survey responses threatening the integrity of our screening survey. In this post, I describe the challenge and suggest strategies to mitigate or even avoid it for future studies.
